399820831 has 2 divisors, whose sum is σ = 399820832. Its totient is φ = 399820830.

The previous prime is 399820763. The next prime is 399820847. The reversal of 399820831 is 138028993.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-399820831 is a prime.

It is a super-2 number, since 2×399820831² = 319713393803061122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399820871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199910415 + 199910416.

It is an arithmetic number, because the mean of its divisors is an integer number (199910416).

Almost surely, 2^399820831 is an apocalyptic number.

399820831 is a deficient number, since it is larger than the sum of its proper divisors (1).

399820831 is an equidigital number, since it uses as much as digits as its factorization.

399820831 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 93312, while the sum is 43.

The square root of 399820831 is about 19995.5202733012. The cubic root of 399820831 is about 736.6962725920.

The spelling of 399820831 in words is "three hundred ninety-nine million, eight hundred twenty thousand, eight hundred thirty-one".