81575812 has 6 divisors (see below), whose sum is σ = 142757678. Its totient is φ = 40787904.

The previous prime is 81575807. The next prime is 81575827. The reversal of 81575812 is 21857518.

It can be written as a sum of positive squares in only one way, i.e., 78428736 + 3147076 = 8856^2 + 1774^2 .

It is a super-2 number, since 2×81575812² = 13309226206918688, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10196973 + ... + 10196980.

Almost surely, 2^81575812 is an apocalyptic number.

It is an amenable number.

81575812 is a deficient number, since it is larger than the sum of its proper divisors (61181866).

81575812 is a wasteful number, since it uses less digits than its factorization.

81575812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20393957 (or 20393955 counting only the distinct ones).

The product of its digits is 22400, while the sum is 37.

The square root of 81575812 is about 9031.9329049767. The cubic root of 81575812 is about 433.6977161274.

The spelling of 81575812 in words is "eighty-one million, five hundred seventy-five thousand, eight hundred twelve".