81199100 has 18 divisors (see below), whose sum is σ = 176202264. Its totient is φ = 32479600.

The previous prime is 81199099. The next prime is 81199133. The reversal of 81199100 is 199118.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 405896 + ... + 406095.

Almost surely, 2^81199100 is an apocalyptic number.

It is an amenable number.

81199100 is an abundant number, since it is smaller than the sum of its proper divisors (95003164).

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

81199100 is a wasteful number, since it uses less digits than its factorization.

81199100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 812005 (or 811998 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 29.

The square root of 81199100 is about 9011.0543223310. The cubic root of 81199100 is about 433.0290895302.

The spelling of 81199100 in words is "eighty-one million, one hundred ninety-nine thousand, one hundred".