81681672402 has 32 divisors (see below), whose sum is σ = 198016176960. Its totient is φ = 24752021760.

The previous prime is 81681672389. The next prime is 81681672431. The reversal of 81681672402 is 20427618618.

81681672402 is a `hidden beast` number, since 8 + 168 + 16 + 72 + 402 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 68755023 + ... + 68756210.

It is an arithmetic number, because the mean of its divisors is an integer number (6188005530).

Almost surely, 2^81681672402 is an apocalyptic number.

81681672402 is an abundant number, since it is smaller than the sum of its proper divisors (116334504558).

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

81681672402 is a wasteful number, since it uses less digits than its factorization.

81681672402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137511255 (or 137511249 counting only the distinct ones).

The product of its (nonzero) digits is 258048, while the sum is 45.

The spelling of 81681672402 in words is "eighty-one billion, six hundred eighty-one million, six hundred seventy-two thousand, four hundred two".