81666680 has 32 divisors (see below), whose sum is σ = 185477040. Its totient is φ = 32359680.

The previous prime is 81666671. The next prime is 81666701. The reversal of 81666680 is 8666618.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5261 + ... + 13820.

Almost surely, 2^81666680 is an apocalyptic number.

It is an amenable number.

81666680 is an abundant number, since it is smaller than the sum of its proper divisors (103810360).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81666680 is a wasteful number, since it uses less digits than its factorization.

81666680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19199 (or 19195 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 41.

The square root of 81666680 is about 9036.9618788617. The cubic root of 81666680 is about 433.8586895801.

The spelling of 81666680 in words is "eighty-one million, six hundred sixty-six thousand, six hundred eighty".