399256566 has 32 divisors (see below), whose sum is σ = 821359968. Its totient is φ = 129288960.

The previous prime is 399256553. The next prime is 399256573. The reversal of 399256566 is 665652993.

It is a super-2 number, since 2×399256566² = 318811610988224712, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 228456 + ... + 230196.

It is an arithmetic number, because the mean of its divisors is an integer number (25667499).

Almost surely, 2^399256566 is an apocalyptic number.

399256566 is an abundant number, since it is smaller than the sum of its proper divisors (422103402).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

399256566 is a wasteful number, since it uses less digits than its factorization.

399256566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2816.

The product of its digits is 2624400, while the sum is 51.

The square root of 399256566 is about 19981.4055061199. The cubic root of 399256566 is about 736.3495442593.

The spelling of 399256566 in words is "three hundred ninety-nine million, two hundred fifty-six thousand, five hundred sixty-six".