81666392 has 24 divisors (see below), whose sum is σ = 154797300. Its totient is φ = 40389840.

The previous prime is 81666379. The next prime is 81666413. The reversal of 81666392 is 29366618.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 301217 + ... + 301487.

Almost surely, 2^81666392 is an apocalyptic number.

It is an amenable number.

81666392 is a deficient number, since it is larger than the sum of its proper divisors (73130908).

81666392 is a wasteful number, since it uses less digits than its factorization.

81666392 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 687 (or 412 counting only the distinct ones).

The product of its digits is 93312, while the sum is 41.

The square root of 81666392 is about 9036.9459442889. The cubic root of 81666392 is about 433.8581795743.

The spelling of 81666392 in words is "eighty-one million, six hundred sixty-six thousand, three hundred ninety-two".