79961891 has 2 divisors, whose sum is σ = 79961892. Its totient is φ = 79961890.

The previous prime is 79961881. The next prime is 79961923. The reversal of 79961891 is 19816997.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 79961891 - 2¹⁴ = 79945507 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (79961821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39980945 + 39980946.

It is an arithmetic number, because the mean of its divisors is an integer number (39980946).

Almost surely, 2^79961891 is an apocalyptic number.

79961891 is a deficient number, since it is larger than the sum of its proper divisors (1).

79961891 is an equidigital number, since it uses as much as digits as its factorization.

79961891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 244944, while the sum is 50.

The square root of 79961891 is about 8942.1412983692. The cubic root of 79961891 is about 430.8185076797.

The spelling of 79961891 in words is "seventy-nine million, nine hundred sixty-one thousand, eight hundred ninety-one".