399686993 has 2 divisors, whose sum is σ = 399686994. Its totient is φ = 399686992.

The previous prime is 399686971. The next prime is 399687023.

It is a happy number.

399686993 is nontrivially palindromic in base 10.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 209467729 + 190219264 = 14473^2 + 13792^2 .

It is a palprime.

It is a cyclic number.

It is not a de Polignac number, because 399686993 - 2⁶ = 399686929 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (399686933) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199843496 + 199843497.

It is an arithmetic number, because the mean of its divisors is an integer number (199843497).

Almost surely, 2^399686993 is an apocalyptic number.

It is an amenable number.

399686993 is a deficient number, since it is larger than the sum of its proper divisors (1).

399686993 is an equidigital number, since it uses as much as digits as its factorization.

399686993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17006112, while the sum is 62.

The square root of 399686993 is about 19992.1732935667. The cubic root of 399686993 is about 736.6140616349.

The spelling of 399686993 in words is "three hundred ninety-nine million, six hundred eighty-six thousand, nine hundred ninety-three".