81597924 has 36 divisors (see below), whose sum is σ = 207589564. Its totient is φ = 27024192.

The previous prime is 81597911. The next prime is 81597947. The reversal of 81597924 is 42979518.

It can be written as a sum of positive squares in 2 ways, for example, as 32148900 + 49449024 = 5670^2 + 7032^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×81597924² = 13316442402219552, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81597924.

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, 1567 + ... + 12870.

Almost surely, 2^81597924 is an apocalyptic number.

It is an amenable number.

81597924 is an abundant number, since it is smaller than the sum of its proper divisors (125991640).

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

81597924 is a wasteful number, since it uses less digits than its factorization.

81597924 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14604 (or 14599 counting only the distinct ones).

The product of its digits is 181440, while the sum is 45.

The square root of 81597924 is about 9033.1569232467. The cubic root of 81597924 is about 433.7368987287.

It can be divided in two parts, 815979 and 24, that added together give a triangular number (816003 = T₁₂₇₇).

The spelling of 81597924 in words is "eighty-one million, five hundred ninety-seven thousand, nine hundred twenty-four".