7899779917 has 2 divisors, whose sum is σ = 7899779918. Its totient is φ = 7899779916.

The previous prime is 7899779869. The next prime is 7899779957. The reversal of 7899779917 is 7199779987.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7819157476 + 80622441 = 88426^2 + 8979^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7899779917 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 7899779917.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7899779957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3949889958 + 3949889959.

It is an arithmetic number, because the mean of its divisors is an integer number (3949889959).

Almost surely, 2^7899779917 is an apocalyptic number.

It is an amenable number.

7899779917 is a deficient number, since it is larger than the sum of its proper divisors (1).

7899779917 is an equidigital number, since it uses as much as digits as its factorization.

7899779917 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 126023688, while the sum is 73.

The square root of 7899779917 is about 88880.7061009306. The cubic root of 7899779917 is about 1991.6132064228.

The spelling of 7899779917 in words is "seven billion, eight hundred ninety-nine million, seven hundred seventy-nine thousand, nine hundred seventeen".