399121913 has 2 divisors, whose sum is σ = 399121914. Its totient is φ = 399121912.

The previous prime is 399121909. The next prime is 399121927. The reversal of 399121913 is 319121993.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 313892089 + 85229824 = 17717^2 + 9232^2 .

It is a cyclic number.

It is not a de Polignac number, because 399121913 - 2² = 399121909 is a prime.

It is not a weakly prime, because it can be changed into another prime (399121013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199560956 + 199560957.

It is an arithmetic number, because the mean of its divisors is an integer number (199560957).

Almost surely, 2^399121913 is an apocalyptic number.

It is an amenable number.

399121913 is a deficient number, since it is larger than the sum of its proper divisors (1).

399121913 is an equidigital number, since it uses as much as digits as its factorization.

399121913 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13122, while the sum is 38.

The square root of 399121913 is about 19978.0357643088. The cubic root of 399121913 is about 736.2667547013.

The spelling of 399121913 in words is "three hundred ninety-nine million, one hundred twenty-one thousand, nine hundred thirteen".