79221557 has 2 divisors, whose sum is σ = 79221558. Its totient is φ = 79221556.

The previous prime is 79221509. The next prime is 79221559. The reversal of 79221557 is 75512297.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 77598481 + 1623076 = 8809^2 + 1274^2 .

It is a cyclic number.

It is not a de Polignac number, because 79221557 - 2¹² = 79217461 is a prime.

Together with 79221559, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 79221557.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (79221559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39610778 + 39610779.

It is an arithmetic number, because the mean of its divisors is an integer number (39610779).

Almost surely, 2^79221557 is an apocalyptic number.

It is an amenable number.

79221557 is a deficient number, since it is larger than the sum of its proper divisors (1).

79221557 is an equidigital number, since it uses as much as digits as its factorization.

79221557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 44100, while the sum is 38.

The square root of 79221557 is about 8900.6492459820. The cubic root of 79221557 is about 429.4847930801.

The spelling of 79221557 in words is "seventy-nine million, two hundred twenty-one thousand, five hundred fifty-seven".