81696672 has 36 divisors (see below), whose sum is σ = 232325730. Its totient is φ = 27232128.

The previous prime is 81696661. The next prime is 81696697. The reversal of 81696672 is 27669618.

It can be written as a sum of positive squares in only one way, i.e., 76108176 + 5588496 = 8724^2 + 2364^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 141547 + ... + 142122.

Almost surely, 2^81696672 is an apocalyptic number.

It is an amenable number.

81696672 is an abundant number, since it is smaller than the sum of its proper divisors (150629058).

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

81696672 is a wasteful number, since it uses less digits than its factorization.

81696672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 283685 (or 283674 counting only the distinct ones).

The product of its digits is 217728, while the sum is 45.

The square root of 81696672 is about 9038.6211337792. The cubic root of 81696672 is about 433.9117944581.

It can be divided in two parts, 8169 and 6672, that added together give a palindrome (14841).

The spelling of 81696672 in words is "eighty-one million, six hundred ninety-six thousand, six hundred seventy-two".