81899372 has 12 divisors (see below), whose sum is σ = 143426136. Its totient is φ = 40920480.

The previous prime is 81899369. The next prime is 81899381. The reversal of 81899372 is 27399818.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 233 + ... + 12800.

It is an arithmetic number, because the mean of its divisors is an integer number (11952178).

Almost surely, 2^81899372 is an apocalyptic number.

It is an amenable number.

81899372 is a deficient number, since it is larger than the sum of its proper divisors (61526764).

81899372 is a wasteful number, since it uses less digits than its factorization.

81899372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14608 (or 14606 counting only the distinct ones).

The product of its digits is 217728, while the sum is 47.

The square root of 81899372 is about 9049.8271806704. The cubic root of 81899372 is about 434.2703618147.

The spelling of 81899372 in words is "eighty-one million, eight hundred ninety-nine thousand, three hundred seventy-two".