78979391 has 2 divisors, whose sum is σ = 78979392. Its totient is φ = 78979390.

The previous prime is 78979363. The next prime is 78979403. The reversal of 78979391 is 19397987.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78979391 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78979301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39489695 + 39489696.

It is an arithmetic number, because the mean of its divisors is an integer number (39489696).

Almost surely, 2^78979391 is an apocalyptic number.

78979391 is a deficient number, since it is larger than the sum of its proper divisors (1).

78979391 is an equidigital number, since it uses as much as digits as its factorization.

78979391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 857304, while the sum is 53.

The square root of 78979391 is about 8887.0349948675. The cubic root of 78979391 is about 429.0467272507.

The spelling of 78979391 in words is "seventy-eight million, nine hundred seventy-nine thousand, three hundred ninety-one".