79121221 has 2 divisors, whose sum is σ = 79121222. Its totient is φ = 79121220.

The previous prime is 79121167. The next prime is 79121227. The reversal of 79121221 is 12212197.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79121025 + 196 = 8895^2 + 14^2 .

It is an emirp because it is prime and its reverse (12212197) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 79121221 - 2¹⁵ = 79088453 is a prime.

It is a super-2 number, since 2×79121221² = 12520335225061682, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (79121227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39560610 + 39560611.

It is an arithmetic number, because the mean of its divisors is an integer number (39560611).

Almost surely, 2^79121221 is an apocalyptic number.

It is an amenable number.

79121221 is a deficient number, since it is larger than the sum of its proper divisors (1).

79121221 is an equidigital number, since it uses as much as digits as its factorization.

79121221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 504, while the sum is 25.

The square root of 79121221 is about 8895.0110174187. The cubic root of 79121221 is about 429.3033988850.

The spelling of 79121221 in words is "seventy-nine million, one hundred twenty-one thousand, two hundred twenty-one".