Expresses a given decimal number in an arbitrary unique letter base. PHP

letters.php

<?php

/**
 * Expresses a given number in a a-z letter base, e.g.:
 * 0 -> a, 27 -> ba, 932 -> bjw, ...
 *
 * @param int $number
 *
 * @return string
*/
function numberInLetters($number)
{
    $numberInLetters = '';

    // 26 letters a-z
    $letters = range('a', 'z');
    $baseSize = count($letters);

    // Remainder that we have to express in letters.
    $remainder = $number;

    // What's the biggest power of base size that we can use for deducting?
    $power = $remainder > 0 ? (int)floor(log($remainder, $baseSize)) : 0;

    while ($power > -1) {
        // Our current base expressed in numbers
        $base = (int)pow($baseSize, $power);

        // How many items of current base can we deduct from the remainder?
        $items = (int)floor($remainder / $base);

        // Deduct as many items of base from remainder.
        $remainder -= ($items * $base);

        // Append this deducted sum expressed in a letter for this base.
        $numberInLetters .= $letters[$items];

        // Move on to the lower power.
        $power--;
    }

    return $numberInLetters;
}