81697524 has 48 divisors (see below), whose sum is σ = 203589120. Its totient is φ = 25441920.

The previous prime is 81697519. The next prime is 81697537. The reversal of 81697524 is 42579618.

It is a hoax number, since the sum of its digits (42) coincides with the sum of the digits of its distinct prime factors.

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, 7002 + ... + 14574.

It is an arithmetic number, because the mean of its divisors is an integer number (4241440).

Almost surely, 2^81697524 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 81697524, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101794560).

81697524 is an abundant number, since it is smaller than the sum of its proper divisors (121891596).

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

81697524 is a wasteful number, since it uses less digits than its factorization.

81697524 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7640 (or 7638 counting only the distinct ones).

The product of its digits is 120960, while the sum is 42.

The square root of 81697524 is about 9038.6682647390. The cubic root of 81697524 is about 433.9133028490.

The spelling of 81697524 in words is "eighty-one million, six hundred ninety-seven thousand, five hundred twenty-four".