81791856 has 120 divisors (see below), whose sum is σ = 240800560. Its totient is φ = 26873856.

The previous prime is 81791837. The next prime is 81791863. The reversal of 81791856 is 65819718.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 423696 + ... + 423888.

Almost surely, 2^81791856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81791856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120400280).

81791856 is an abundant number, since it is smaller than the sum of its proper divisors (159008704).

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

81791856 is a wasteful number, since it uses less digits than its factorization.

81791856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 325 (or 307 counting only the distinct ones).

The product of its digits is 120960, while the sum is 45.

The square root of 81791856 is about 9043.8850059032. The cubic root of 81791856 is about 434.0802445293.

The spelling of 81791856 in words is "eighty-one million, seven hundred ninety-one thousand, eight hundred fifty-six".