399565440 has 256 divisors, whose sum is σ = 1490832000. Its totient is φ = 100859904.

The previous prime is 399565429. The next prime is 399565457. The reversal of 399565440 is 44565993.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 327712 + ... + 328928.

Almost surely, 2^399565440 is an apocalyptic number.

399565440 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 399565440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (745416000).

399565440 is an abundant number, since it is smaller than the sum of its proper divisors (1091266560).

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

399565440 is a wasteful number, since it uses less digits than its factorization.

399565440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1264 (or 1246 counting only the distinct ones).

The product of its (nonzero) digits is 583200, while the sum is 45.

The square root of 399565440 is about 19989.1330477337. The cubic root of 399565440 is about 736.5393809232.

The spelling of 399565440 in words is "three hundred ninety-nine million, five hundred sixty-five thousand, four hundred forty".