81997684 has 12 divisors (see below), whose sum is σ = 144069408. Its totient is φ = 40835000.

The previous prime is 81997679. The next prime is 81997717. The reversal of 81997684 is 48679918.

It is a happy number.

It is a congruent number.

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, 39832 + ... + 41839.

It is an arithmetic number, because the mean of its divisors is an integer number (12005784).

Almost surely, 2^81997684 is an apocalyptic number.

It is an amenable number.

81997684 is a deficient number, since it is larger than the sum of its proper divisors (62071724).

81997684 is a wasteful number, since it uses less digits than its factorization.

81997684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81926 (or 81924 counting only the distinct ones).

The product of its digits is 870912, while the sum is 52.

The square root of 81997684 is about 9055.2572575273. The cubic root of 81997684 is about 434.4440583680. Note that the first 3 decimals are identical.

The spelling of 81997684 in words is "eighty-one million, nine hundred ninety-seven thousand, six hundred eighty-four".