81800788 has 12 divisors (see below), whose sum is σ = 149375520. Its totient is φ = 39122072.

The previous prime is 81800759. The next prime is 81800791. The reversal of 81800788 is 88700818.

It is a self number, because there is not a number n which added to its sum of digits gives 81800788.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 444478 + ... + 444661.

It is an arithmetic number, because the mean of its divisors is an integer number (12447960).

Almost surely, 2^81800788 is an apocalyptic number.

It is an amenable number.

81800788 is a deficient number, since it is larger than the sum of its proper divisors (67574732).

81800788 is a wasteful number, since it uses less digits than its factorization.

81800788 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 889166 (or 889164 counting only the distinct ones).

The product of its (nonzero) digits is 28672, while the sum is 40.

The square root of 81800788 is about 9044.3788067506. The cubic root of 81800788 is about 434.0960450576.

The spelling of 81800788 in words is "eighty-one million, eight hundred thousand, seven hundred eighty-eight".