81644932 has 6 divisors (see below), whose sum is σ = 142878638. Its totient is φ = 40822464.

The previous prime is 81644929. The next prime is 81644933. The reversal of 81644932 is 23944618.

It can be written as a sum of positive squares in only one way, i.e., 72318016 + 9326916 = 8504^2 + 3054^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81644891 and 81644900.

It is not an unprimeable number, because it can be changed into a prime (81644933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10205613 + ... + 10205620.

Almost surely, 2^81644932 is an apocalyptic number.

It is an amenable number.

81644932 is a deficient number, since it is larger than the sum of its proper divisors (61233706).

81644932 is a wasteful number, since it uses less digits than its factorization.

81644932 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20411237 (or 20411235 counting only the distinct ones).

The product of its digits is 41472, while the sum is 37.

The square root of 81644932 is about 9035.7585182429. The cubic root of 81644932 is about 433.8201736824.

The spelling of 81644932 in words is "eighty-one million, six hundred forty-four thousand, nine hundred thirty-two".