81636672 has 56 divisors (see below), whose sum is σ = 232619296. Its totient is φ = 25118208.

The previous prime is 81636649. The next prime is 81636679. The reversal of 81636672 is 27663618.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a self number, because there is not a number n which added to its sum of digits gives 81636672.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81636679) 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, 13858 + ... + 18849.

It is an arithmetic number, because the mean of its divisors is an integer number (4153916).

Almost surely, 2^81636672 is an apocalyptic number.

It is an amenable number.

81636672 is an abundant number, since it is smaller than the sum of its proper divisors (150982624).

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

81636672 is a wasteful number, since it uses less digits than its factorization.

81636672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32735 (or 32725 counting only the distinct ones).

The product of its digits is 72576, while the sum is 39.

The square root of 81636672 is about 9035.3014338206. The cubic root of 81636672 is about 433.8055433582.

The spelling of 81636672 in words is "eighty-one million, six hundred thirty-six thousand, six hundred seventy-two".