81216504 has 48 divisors (see below), whose sum is σ = 220849200. Its totient is φ = 26962944.

The previous prime is 81216493. The next prime is 81216521. The reversal of 81216504 is 40561218.

81216504 is a `hidden beast` number, since 8 + 1 + 2 + 1 + 650 + 4 = 666.

It is a super-2 number, since 2×81216504² = 13192241043964032, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16792 + ... + 21080.

It is an arithmetic number, because the mean of its divisors is an integer number (4601025).

Almost surely, 2^81216504 is an apocalyptic number.

It is an amenable number.

81216504 is an abundant number, since it is smaller than the sum of its proper divisors (139632696).

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

81216504 is a wasteful number, since it uses less digits than its factorization.

81216504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4564 (or 4557 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 81216504 is about 9012.0199733467. The cubic root of 81216504 is about 433.0600254227.

The spelling of 81216504 in words is "eighty-one million, two hundred sixteen thousand, five hundred four".