81779872 has 24 divisors (see below), whose sum is σ = 162279936. Its totient is φ = 40565952.

The previous prime is 81779869. The next prime is 81779903. The reversal of 81779872 is 27897718.

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, 5998 + ... + 14125.

It is an arithmetic number, because the mean of its divisors is an integer number (6761664).

Almost surely, 2^81779872 is an apocalyptic number.

It is an amenable number.

81779872 is a deficient number, since it is larger than the sum of its proper divisors (80500064).

81779872 is a wasteful number, since it uses less digits than its factorization.

81779872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20260 (or 20252 counting only the distinct ones).

The product of its digits is 395136, while the sum is 49.

The square root of 81779872 is about 9043.2224345086. Note that the first 3 decimals coincide. The cubic root of 81779872 is about 434.0590432672.

The spelling of 81779872 in words is "eighty-one million, seven hundred seventy-nine thousand, eight hundred seventy-two".