81691304 has 16 divisors (see below), whose sum is σ = 154029600. Its totient is φ = 40616752.

The previous prime is 81691297. The next prime is 81691321. The reversal of 81691304 is 40319618.

It is a happy 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, 27092 + ... + 29955.

It is an arithmetic number, because the mean of its divisors is an integer number (9626850).

Almost surely, 2^81691304 is an apocalyptic number.

It is an amenable number.

81691304 is a deficient number, since it is larger than the sum of its proper divisors (72338296).

81691304 is a wasteful number, since it uses less digits than its factorization.

81691304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57232 (or 57228 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 32.

The square root of 81691304 is about 9038.3241809530. The cubic root of 81691304 is about 433.9022906457.

The spelling of 81691304 in words is "eighty-one million, six hundred ninety-one thousand, three hundred four".