79171921 has 2 divisors, whose sum is σ = 79171922. Its totient is φ = 79171920.

The previous prime is 79171919. The next prime is 79171933. The reversal of 79171921 is 12917197.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78588225 + 583696 = 8865^2 + 764^2 .

It is a cyclic number.

It is not a de Polignac number, because 79171921 - 2¹ = 79171919 is a prime.

Together with 79171919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (79171321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39585960 + 39585961.

It is an arithmetic number, because the mean of its divisors is an integer number (39585961).

Almost surely, 2^79171921 is an apocalyptic number.

It is an amenable number.

79171921 is a deficient number, since it is larger than the sum of its proper divisors (1).

79171921 is an equidigital number, since it uses as much as digits as its factorization.

79171921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7938, while the sum is 37.

The square root of 79171921 is about 8897.8604731699. The cubic root of 79171921 is about 429.3950769230.

The spelling of 79171921 in words is "seventy-nine million, one hundred seventy-one thousand, nine hundred twenty-one".