399831989 has 2 divisors, whose sum is σ = 399831990. Its totient is φ = 399831988.

The previous prime is 399831983. The next prime is 399832009. The reversal of 399831989 is 989138993.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 362255089 + 37576900 = 19033^2 + 6130^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-399831989 is a prime.

It is a super-2 number, since 2×399831989² = 319731238855392242, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399831983) 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, 199915994 + 199915995.

It is an arithmetic number, because the mean of its divisors is an integer number (199915995).

Almost surely, 2^399831989 is an apocalyptic number.

It is an amenable number.

399831989 is a deficient number, since it is larger than the sum of its proper divisors (1).

399831989 is an equidigital number, since it uses as much as digits as its factorization.

399831989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3779136, while the sum is 59.

The square root of 399831989 is about 19995.7992838496. The cubic root of 399831989 is about 736.7031256454.

The spelling of 399831989 in words is "three hundred ninety-nine million, eight hundred thirty-one thousand, nine hundred eighty-nine".