81699800 has 144 divisors (see below), whose sum is σ = 237328560. Its totient is φ = 25470720.

The previous prime is 81699799. The next prime is 81699823. The reversal of 81699800 is 899618.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1219367 + ... + 1219433.

It is an arithmetic number, because the mean of its divisors is an integer number (1648115).

Almost surely, 2^81699800 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81699800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118664280).

81699800 is an abundant number, since it is smaller than the sum of its proper divisors (155628760).

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

81699800 is a wasteful number, since it uses less digits than its factorization.

81699800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170 (or 94 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 41.

The square root of 81699800 is about 9038.7941673655. The cubic root of 81699800 is about 433.9173322552.

The spelling of 81699800 in words is "eighty-one million, six hundred ninety-nine thousand, eight hundred".