399638929 has 2 divisors, whose sum is σ = 399638930. Its totient is φ = 399638928.

The previous prime is 399638927. The next prime is 399638957. The reversal of 399638929 is 929836993.

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., 396209025 + 3429904 = 19905^2 + 1852^2 .

It is a cyclic number.

It is not a de Polignac number, because 399638929 - 2¹ = 399638927 is a prime.

It is a super-2 number, since 2×399638929² = 319422547144534082, which contains 22 as substring.

Together with 399638927, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (399638923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199819464 + 199819465.

It is an arithmetic number, because the mean of its divisors is an integer number (199819465).

Almost surely, 2^399638929 is an apocalyptic number.

It is an amenable number.

399638929 is a deficient number, since it is larger than the sum of its proper divisors (1).

399638929 is an equidigital number, since it uses as much as digits as its factorization.

399638929 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5668704, while the sum is 58.

The square root of 399638929 is about 19990.9711870134. The cubic root of 399638929 is about 736.5845334973.

The spelling of 399638929 in words is "three hundred ninety-nine million, six hundred thirty-eight thousand, nine hundred twenty-nine".