81659900 has 36 divisors (see below), whose sum is σ = 202518288. Its totient is φ = 27997440.

The previous prime is 81659899. The next prime is 81659923. The reversal of 81659900 is 995618.

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, 57629 + ... + 59028.

It is an arithmetic number, because the mean of its divisors is an integer number (5625508).

Almost surely, 2^81659900 is an apocalyptic number.

It is an amenable number.

81659900 is an abundant number, since it is smaller than the sum of its proper divisors (120858388).

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

81659900 is a wasteful number, since it uses less digits than its factorization.

81659900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116678 (or 116671 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 38.

The square root of 81659900 is about 9036.5867450050. The cubic root of 81659900 is about 433.8466828746.

The spelling of 81659900 in words is "eighty-one million, six hundred fifty-nine thousand, nine hundred".