81199400 has 24 divisors (see below), whose sum is σ = 188789070. Its totient is φ = 32479680.

The previous prime is 81199397. The next prime is 81199403. The reversal of 81199400 is 499118.

It is an interprime number because it is at equal distance from previous prime (81199397) and next prime (81199403).

It can be written as a sum of positive squares in 3 ways, for example, as 57365476 + 23833924 = 7574^2 + 4882^2 .

It is not an unprimeable number, because it can be changed into a prime (81199403) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 202799 + ... + 203198.

Almost surely, 2^81199400 is an apocalyptic number.

It is an amenable number.

81199400 is an abundant number, since it is smaller than the sum of its proper divisors (107589670).

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

81199400 is a wasteful number, since it uses less digits than its factorization.

81199400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406013 (or 406004 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 81199400 is about 9011.0709685364. The cubic root of 81199400 is about 433.0296228225.

The spelling of 81199400 in words is "eighty-one million, one hundred ninety-nine thousand, four hundred".