CI 3 or 4 number helper with large number abbreviations.

number_helper.php

<?php
function number_to_amount($value, bool $abbreviate = false):string
{
  $iLimit = 90;
  $sLimit = 'Octovigintillion';
  if(strlen($value) > $iLimit)
  {
    throw new Exception("The value must not exceed $sLimit.");
  }
  $unit = '';
  $symbol = $abbreviate ? 'K' : 'Thousand';
  $iThousand = 1000;
  while($value >= $iThousand) 
  {
    $value /= $iThousand;
    $unit .= $symbol;
  }
  $units = 
  [
    ['Million', 'M'],
    ['Billion', 'B'],
    ['Trillion', 't'],
    ['Quadrillion', 'q'],
    ['Quintillion', 'Q'],
    ['Sextillion', 's'],
    ['Septillion', 'S'],
    ['Octillion', 'o'],
    ['Nonillion', 'n'],
    ['Decillion', 'd'],
    ['Undecillion', 'U'],
    ['Duodecillion', 'D'],
    ['Tredecillion', 'T'],
    ['Quattuordecillion', 'Qt'],
    ['Quindecillion', 'Qd'],
    ['Sexdecillion', 'Sd'],
    ['Septendecillion', 'St'],
    ['Octodecillion', 'O'],
    ['Novemdecillion', 'N'],
    ['Vigintillion', 'v'],
    ['Unvigintillion', 'c'],
    ['Duovigintillion', 'e69'],
    ['Trevigintillion', 'e72'],
    ['Quattuorvigintillion', 'e75'],
    ['Quinvigintillion', 'e78'],
    ['Sesvigintillion', 'e81'],
    ['Septenvigintillion', 'e84'],
    [$sLimit, 'e87']
  ];
  $j = count($units);
  for($i = $j - 1; $i > -1; $i--)
  {
    $iSymbolOffset = 2;
    $search = str_repeat($symbol, $i + $iSymbolOffset);
    $replace = $units[$i][$abbreviate];
    $unit = str_replace($search, $replace, $unit);
  }
  $separator = $abbreviate ? '': ' ';
  $amt = $value. $separator . $unit;
  return $abbreviate ? $amt : strtolower($amt);
}
function init()
{
  foreach(range(0, 90) as $i)
  {
    $zeros = str_repeat('0', $i);
    $i = (int)1 . $zeros;
    $amt = number_to_amount($i, true);
    echo $i, ' = ', $amt, "<br>\r\n";
  }
}
init();