81099372 has 72 divisors (see below), whose sum is σ = 202820016. Its totient is φ = 25214976.

The previous prime is 81099371. The next prime is 81099373. The reversal of 81099372 is 27399018.

It is an interprime number because it is at equal distance from previous prime (81099371) and next prime (81099373).

It is a self number, because there is not a number n which added to its sum of digits gives 81099372.

It is not an unprimeable number, because it can be changed into a prime (81099371) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 420108 + ... + 420300.

Almost surely, 2^81099372 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 81099372, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101410008).

81099372 is an abundant number, since it is smaller than the sum of its proper divisors (121720644).

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

81099372 is a wasteful number, since it uses less digits than its factorization.

81099372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 335 (or 314 counting only the distinct ones).

The product of its (nonzero) digits is 27216, while the sum is 39.

The square root of 81099372 is about 9005.5189744956. The cubic root of 81099372 is about 432.8517360990.

The spelling of 81099372 in words is "eighty-one million, ninety-nine thousand, three hundred seventy-two".