399638557 has 2 divisors, whose sum is σ = 399638558. Its totient is φ = 399638556.

The previous prime is 399638537. The next prime is 399638587. The reversal of 399638557 is 755836993.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 280261081 + 119377476 = 16741^2 + 10926^2 .

It is a cyclic number.

It is not a de Polignac number, because 399638557 - 2¹¹ = 399636509 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 399638498 and 399638507.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399638537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199819278 + 199819279.

It is an arithmetic number, because the mean of its divisors is an integer number (199819279).

Almost surely, 2^399638557 is an apocalyptic number.

It is an amenable number.

399638557 is a deficient number, since it is larger than the sum of its proper divisors (1).

399638557 is an equidigital number, since it uses as much as digits as its factorization.

399638557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6123600, while the sum is 55.

The square root of 399638557 is about 19990.9618828109. The cubic root of 399638557 is about 736.5843049498.

The spelling of 399638557 in words is "three hundred ninety-nine million, six hundred thirty-eight thousand, five hundred fifty-seven".