81939372 has 24 divisors (see below), whose sum is σ = 191352000. Its totient is φ = 27290256.

The previous prime is 81939367. The next prime is 81939373. The reversal of 81939372 is 27393918.

It is not an unprimeable number, because it can be changed into a prime (81939373) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18379 + ... + 22397.

It is an arithmetic number, because the mean of its divisors is an integer number (7973000).

Almost surely, 2^81939372 is an apocalyptic number.

It is an amenable number.

81939372 is an abundant number, since it is smaller than the sum of its proper divisors (109412628).

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

81939372 is a wasteful number, since it uses less digits than its factorization.

81939372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5725 (or 5723 counting only the distinct ones).

The product of its digits is 81648, while the sum is 42.

The square root of 81939372 is about 9052.0368978479. The cubic root of 81939372 is about 434.3410501355.

The spelling of 81939372 in words is "eighty-one million, nine hundred thirty-nine thousand, three hundred seventy-two".