399663281 has 2 divisors, whose sum is σ = 399663282. Its totient is φ = 399663280.

The previous prime is 399663263. The next prime is 399663287. The reversal of 399663281 is 182366993.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 249355681 + 150307600 = 15791^2 + 12260^2 .

It is a cyclic number.

It is not a de Polignac number, because 399663281 - 2¹⁰ = 399662257 is a prime.

It is a super-2 number, since 2×399663281² = 319461476359369922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (399663287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199831640 + 199831641.

It is an arithmetic number, because the mean of its divisors is an integer number (199831641).

Almost surely, 2^399663281 is an apocalyptic number.

It is an amenable number.

399663281 is a deficient number, since it is larger than the sum of its proper divisors (1).

399663281 is an equidigital number, since it uses as much as digits as its factorization.

399663281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 419904, while the sum is 47.

The square root of 399663281 is about 19991.5802526964. The cubic root of 399663281 is about 736.5994944541.

The spelling of 399663281 in words is "three hundred ninety-nine million, six hundred sixty-three thousand, two hundred eighty-one".