81666100 has 36 divisors (see below), whose sum is σ = 184925664. Its totient is φ = 31245280.

The previous prime is 81666071. The next prime is 81666131. The reversal of 81666100 is 166618.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15454 + ... + 20053.

It is an arithmetic number, because the mean of its divisors is an integer number (5136824).

Almost surely, 2^81666100 is an apocalyptic number.

It is an amenable number.

81666100 is an abundant number, since it is smaller than the sum of its proper divisors (103259564).

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

81666100 is a wasteful number, since it uses less digits than its factorization.

81666100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35544 (or 35537 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 81666100 is about 9036.9297883739. The cubic root of 81666100 is about 433.8576624838.

The spelling of 81666100 in words is "eighty-one million, six hundred sixty-six thousand, one hundred".