81517868 has 6 divisors (see below), whose sum is σ = 142656276. Its totient is φ = 40758932.

The previous prime is 81517841. The next prime is 81517901. The reversal of 81517868 is 86871518.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10189730 + ... + 10189737.

It is an arithmetic number, because the mean of its divisors is an integer number (23776046).

Almost surely, 2^81517868 is an apocalyptic number.

It is an amenable number.

81517868 is a deficient number, since it is larger than the sum of its proper divisors (61138408).

81517868 is a wasteful number, since it uses less digits than its factorization.

81517868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20379471 (or 20379469 counting only the distinct ones).

The product of its digits is 107520, while the sum is 44.

The square root of 81517868 is about 9028.7246053914. The cubic root of 81517868 is about 433.5950054004.

The spelling of 81517868 in words is "eighty-one million, five hundred seventeen thousand, eight hundred sixty-eight".