79909891 has 2 divisors, whose sum is σ = 79909892. Its totient is φ = 79909890.

The previous prime is 79909883. The next prime is 79909897. The reversal of 79909891 is 19890997.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 79909891 - 2³ = 79909883 is a prime.

It is not a weakly prime, because it can be changed into another prime (79909897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39954945 + 39954946.

It is an arithmetic number, because the mean of its divisors is an integer number (39954946).

Almost surely, 2^79909891 is an apocalyptic number.

79909891 is a deficient number, since it is larger than the sum of its proper divisors (1).

79909891 is an equidigital number, since it uses as much as digits as its factorization.

79909891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 367416, while the sum is 52.

The square root of 79909891 is about 8939.2332445238. The cubic root of 79909891 is about 430.7250989318.

The spelling of 79909891 in words is "seventy-nine million, nine hundred nine thousand, eight hundred ninety-one".