81601864 has 16 divisors (see below), whose sum is σ = 153251820. Its totient is φ = 40734720.

The previous prime is 81601847. The next prime is 81601867. The reversal of 81601864 is 46810618.

It can be written as a sum of positive squares in 2 ways, for example, as 69056100 + 12545764 = 8310^2 + 3542^2 .

It is not an unprimeable number, because it can be changed into a prime (81601867) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2829 + ... + 13084.

Almost surely, 2^81601864 is an apocalyptic number.

It is an amenable number.

81601864 is a deficient number, since it is larger than the sum of its proper divisors (71649956).

81601864 is a wasteful number, since it uses less digits than its factorization.

81601864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16560 (or 16556 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 34.

The square root of 81601864 is about 9033.3750060539. The cubic root of 81601864 is about 433.7438796901.

The spelling of 81601864 in words is "eighty-one million, six hundred one thousand, eight hundred sixty-four".