779939921 has 2 divisors, whose sum is σ = 779939922. Its totient is φ = 779939920.

The previous prime is 779939869. The next prime is 779940001. The reversal of 779939921 is 129939977.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 488896321 + 291043600 = 22111^2 + 17060^2 .

It is a cyclic number.

It is not a de Polignac number, because 779939921 - 2¹⁸ = 779677777 is a prime.

It is not a weakly prime, because it can be changed into another prime (779939621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 389969960 + 389969961.

It is an arithmetic number, because the mean of its divisors is an integer number (389969961).

Almost surely, 2^779939921 is an apocalyptic number.

It is an amenable number.

779939921 is a deficient number, since it is larger than the sum of its proper divisors (1).

779939921 is an equidigital number, since it uses as much as digits as its factorization.

779939921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1928934, while the sum is 56.

The square root of 779939921 is about 27927.4044801876. The cubic root of 779939921 is about 920.4927735827.

Adding to 779939921 its sum of digits (56), we get a palindrome (779939977).

The spelling of 779939921 in words is "seven hundred seventy-nine million, nine hundred thirty-nine thousand, nine hundred twenty-one".