81639932 has 24 divisors (see below), whose sum is σ = 156137520. Its totient is φ = 37042560.

The previous prime is 81639917. The next prime is 81639937. The reversal of 81639932 is 23993618.

It is a self number, because there is not a number n which added to its sum of digits gives 81639932.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81639937) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29888 + ... + 32504.

It is an arithmetic number, because the mean of its divisors is an integer number (6505730).

Almost surely, 2^81639932 is an apocalyptic number.

It is an amenable number.

81639932 is a deficient number, since it is larger than the sum of its proper divisors (74497588).

81639932 is a wasteful number, since it uses less digits than its factorization.

81639932 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3341 (or 3339 counting only the distinct ones).

The product of its digits is 69984, while the sum is 41.

The square root of 81639932 is about 9035.4818355193. The cubic root of 81639932 is about 433.8113176718.

The spelling of 81639932 in words is "eighty-one million, six hundred thirty-nine thousand, nine hundred thirty-two".