79781857 has 2 divisors, whose sum is σ = 79781858. Its totient is φ = 79781856.

The previous prime is 79781851. The next prime is 79781881. The reversal of 79781857 is 75818797.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55338721 + 24443136 = 7439^2 + 4944^2 .

It is a cyclic number.

It is not a de Polignac number, because 79781857 - 2²³ = 71393249 is a prime.

It is not a weakly prime, because it can be changed into another prime (79781851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39890928 + 39890929.

It is an arithmetic number, because the mean of its divisors is an integer number (39890929).

Almost surely, 2^79781857 is an apocalyptic number.

It is an amenable number.

79781857 is a deficient number, since it is larger than the sum of its proper divisors (1).

79781857 is an equidigital number, since it uses as much as digits as its factorization.

79781857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 987840, while the sum is 52.

The square root of 79781857 is about 8932.0690212291. The cubic root of 79781857 is about 430.4949357824.

The spelling of 79781857 in words is "seventy-nine million, seven hundred eighty-one thousand, eight hundred fifty-seven".