81517856 has 48 divisors (see below), whose sum is σ = 194213376. Its totient is φ = 32879616.

The previous prime is 81517841. The next prime is 81517901. The reversal of 81517856 is 65871518.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6896 + ... + 14511.

It is an arithmetic number, because the mean of its divisors is an integer number (4046112).

Almost surely, 2^81517856 is an apocalyptic number.

It is an amenable number.

81517856 is an abundant number, since it is smaller than the sum of its proper divisors (112695520).

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

81517856 is a wasteful number, since it uses less digits than its factorization.

81517856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21441 (or 21433 counting only the distinct ones).

The product of its digits is 67200, while the sum is 41.

The square root of 81517856 is about 9028.7239408457. The cubic root of 81517856 is about 433.5949841243.

The spelling of 81517856 in words is "eighty-one million, five hundred seventeen thousand, eight hundred fifty-six".