78961657 has 2 divisors, whose sum is σ = 78961658. Its totient is φ = 78961656.

The previous prime is 78961643. The next prime is 78961661. The reversal of 78961657 is 75616987.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 74028816 + 4932841 = 8604^2 + 2221^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78961657 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 78961657.

It is not a weakly prime, because it can be changed into another prime (78961607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39480828 + 39480829.

It is an arithmetic number, because the mean of its divisors is an integer number (39480829).

Almost surely, 2^78961657 is an apocalyptic number.

It is an amenable number.

78961657 is a deficient number, since it is larger than the sum of its proper divisors (1).

78961657 is an equidigital number, since it uses as much as digits as its factorization.

78961657 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 635040, while the sum is 49.

The square root of 78961657 is about 8886.0371932600. The cubic root of 78961657 is about 429.0146121882.

The spelling of 78961657 in words is "seventy-eight million, nine hundred sixty-one thousand, six hundred fifty-seven".