79171891 has 2 divisors, whose sum is σ = 79171892. Its totient is φ = 79171890.

The previous prime is 79171853. The next prime is 79171919. The reversal of 79171891 is 19817197.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-79171891 is a prime.

It is not a weakly prime, because it can be changed into another prime (79171831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39585945 + 39585946.

It is an arithmetic number, because the mean of its divisors is an integer number (39585946).

Almost surely, 2^79171891 is an apocalyptic number.

79171891 is the 5628-th centered pentagonal number.

79171891 is a deficient number, since it is larger than the sum of its proper divisors (1).

79171891 is an equidigital number, since it uses as much as digits as its factorization.

79171891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31752, while the sum is 43.

The square root of 79171891 is about 8897.8587873713. The cubic root of 79171891 is about 429.3950226872.

The spelling of 79171891 in words is "seventy-nine million, one hundred seventy-one thousand, eight hundred ninety-one".