81859900 has 36 divisors (see below), whose sum is σ = 181425888. Its totient is φ = 32045440.

The previous prime is 81859889. The next prime is 81859901. The reversal of 81859900 is 995818.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81859901) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4009 + ... + 13408.

It is an arithmetic number, because the mean of its divisors is an integer number (5039608).

Almost surely, 2^81859900 is an apocalyptic number.

It is an amenable number.

81859900 is an abundant number, since it is smaller than the sum of its proper divisors (99565988).

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

81859900 is a wasteful number, since it uses less digits than its factorization.

81859900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17478 (or 17471 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 40.

The square root of 81859900 is about 9047.6461027164. The cubic root of 81859900 is about 434.2005840135.

The spelling of 81859900 in words is "eighty-one million, eight hundred fifty-nine thousand, nine hundred".