81901656 has 48 divisors (see below), whose sum is σ = 222855360. Its totient is φ = 27172800.

The previous prime is 81901649. The next prime is 81901667. The reversal of 81901656 is 65610918.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 81901656.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13506 + ... + 18606.

It is an arithmetic number, because the mean of its divisors is an integer number (4642820).

Almost surely, 2^81901656 is an apocalyptic number.

It is an amenable number.

81901656 is an abundant number, since it is smaller than the sum of its proper divisors (140953704).

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

81901656 is a wasteful number, since it uses less digits than its factorization.

81901656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5336 (or 5329 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 81901656 is about 9049.9533700456. The cubic root of 81901656 is about 434.2743987373.

The spelling of 81901656 in words is "eighty-one million, nine hundred one thousand, six hundred fifty-six".