81656668 has 12 divisors (see below), whose sum is σ = 143141152. Its totient is φ = 40759200.

The previous prime is 81656657. The next prime is 81656671. The reversal of 81656668 is 86665618.

It is a super-2 number, since 2×81656668² = 13335622857724448, which contains 22 as substring.

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, 14580 + ... + 19387.

Almost surely, 2^81656668 is an apocalyptic number.

It is an amenable number.

81656668 is a deficient number, since it is larger than the sum of its proper divisors (61484484).

81656668 is a wasteful number, since it uses less digits than its factorization.

81656668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34572 (or 34570 counting only the distinct ones).

The product of its digits is 414720, while the sum is 46.

The square root of 81656668 is about 9036.4079146528. The cubic root of 81656668 is about 433.8409590903.

The spelling of 81656668 in words is "eighty-one million, six hundred fifty-six thousand, six hundred sixty-eight".