81621488 has 80 divisors (see below), whose sum is σ = 185050656. Its totient is φ = 34529280.

The previous prime is 81621479. The next prime is 81621493. The reversal of 81621488 is 88412618.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 144695 + ... + 145257.

Almost surely, 2^81621488 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81621488, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (92525328).

81621488 is an abundant number, since it is smaller than the sum of its proper divisors (103429168).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81621488 is a wasteful number, since it uses less digits than its factorization.

81621488 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 642 (or 636 counting only the distinct ones).

The product of its digits is 24576, while the sum is 38.

The square root of 81621488 is about 9034.4611350097. The cubic root of 81621488 is about 433.7786464926.

It can be divided in two parts, 8162 and 1488, that multiplied together give a triangular number (12145056 = T₄₉₂₈).

The spelling of 81621488 in words is "eighty-one million, six hundred twenty-one thousand, four hundred eighty-eight".