78864917 has 2 divisors, whose sum is σ = 78864918. Its totient is φ = 78864916.

The previous prime is 78864913. The next prime is 78864931. The reversal of 78864917 is 71946887.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 67749361 + 11115556 = 8231^2 + 3334^2 .

It is a cyclic number.

It is not a de Polignac number, because 78864917 - 2² = 78864913 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78864913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39432458 + 39432459.

It is an arithmetic number, because the mean of its divisors is an integer number (39432459).

Almost surely, 2^78864917 is an apocalyptic number.

It is an amenable number.

78864917 is a deficient number, since it is larger than the sum of its proper divisors (1).

78864917 is an equidigital number, since it uses as much as digits as its factorization.

78864917 is an evil number, because the sum of its binary digits is even.

The product of its digits is 677376, while the sum is 50.

The square root of 78864917 is about 8880.5921536798. The cubic root of 78864917 is about 428.8393379441.

The spelling of 78864917 in words is "seventy-eight million, eight hundred sixty-four thousand, nine hundred seventeen".