81237921 has 8 divisors (see below), whose sum is σ = 108545280. Its totient is φ = 54044592.

The previous prime is 81237913. The next prime is 81237973. The reversal of 81237921 is 12973218.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81237921 - 2³ = 81237913 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81230921) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26830 + ... + 29703.

It is an arithmetic number, because the mean of its divisors is an integer number (13568160).

Almost surely, 2^81237921 is an apocalyptic number.

It is an amenable number.

81237921 is a deficient number, since it is larger than the sum of its proper divisors (27307359).

81237921 is a wasteful number, since it uses less digits than its factorization.

81237921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57015.

The product of its digits is 6048, while the sum is 33.

The square root of 81237921 is about 9013.2081413889. The cubic root of 81237921 is about 433.0980884229.

The spelling of 81237921 in words is "eighty-one million, two hundred thirty-seven thousand, nine hundred twenty-one".