81700979 has 4 divisors (see below), whose sum is σ = 82202376. Its totient is φ = 81199584.

The previous prime is 81700937. The next prime is 81701029. The reversal of 81700979 is 97900718.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81700979 - 2²⁴ = 64923763 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81700919) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 250454 + ... + 250779.

It is an arithmetic number, because the mean of its divisors is an integer number (20550594).

Almost surely, 2^81700979 is an apocalyptic number.

81700979 is a deficient number, since it is larger than the sum of its proper divisors (501397).

81700979 is a wasteful number, since it uses less digits than its factorization.

81700979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 501396.

The product of its (nonzero) digits is 31752, while the sum is 41.

The square root of 81700979 is about 9038.8593860066. The cubic root of 81700979 is about 433.9194195147.

The spelling of 81700979 in words is "eighty-one million, seven hundred thousand, nine hundred seventy-nine".