81556704 has 36 divisors (see below), whose sum is σ = 231927696. Its totient is φ = 27185472.

The previous prime is 81556697. The next prime is 81556723. The reversal of 81556704 is 40765518.

It is a tau number, because it is divible by the number of its divisors (36).

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 141304 + ... + 141879.

It is an arithmetic number, because the mean of its divisors is an integer number (6442436).

Almost surely, 2^81556704 is an apocalyptic number.

It is an amenable number.

81556704 is an abundant number, since it is smaller than the sum of its proper divisors (150370992).

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

81556704 is a wasteful number, since it uses less digits than its factorization.

81556704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283199 (or 283188 counting only the distinct ones).

The product of its (nonzero) digits is 33600, while the sum is 36.

The square root of 81556704 is about 9030.8750406591. The cubic root of 81556704 is about 433.6638509293.

The spelling of 81556704 in words is "eighty-one million, five hundred fifty-six thousand, seven hundred four".