81800508 has 24 divisors (see below), whose sum is σ = 192264912. Its totient is φ = 27067264.

The previous prime is 81800497. The next prime is 81800513. The reversal of 81800508 is 80500818.

It is a congruent number.

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, 23235 + ... + 26522.

It is an arithmetic number, because the mean of its divisors is an integer number (8011038).

Almost surely, 2^81800508 is an apocalyptic number.

It is an amenable number.

81800508 is an abundant number, since it is smaller than the sum of its proper divisors (110464404).

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

81800508 is a wasteful number, since it uses less digits than its factorization.

81800508 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49901 (or 49899 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 30.

The square root of 81800508 is about 9044.3633275096. The cubic root of 81800508 is about 434.0955497607.

The spelling of 81800508 in words is "eighty-one million, eight hundred thousand, five hundred eight".