399836640 has 192 divisors, whose sum is σ = 1452294144. Its totient is φ = 90574848.

The previous prime is 399836629. The next prime is 399836641. The reversal of 399836640 is 46638993.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 399836640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399836641) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 426252 + ... + 427188.

It is an arithmetic number, because the mean of its divisors is an integer number (7564032).

Almost surely, 2^399836640 is an apocalyptic number.

399836640 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 399836640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (726147072).

399836640 is an abundant number, since it is smaller than the sum of its proper divisors (1052457504).

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

399836640 is a wasteful number, since it uses less digits than its factorization.

399836640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1089 (or 1081 counting only the distinct ones).

The product of its (nonzero) digits is 839808, while the sum is 48.

The square root of 399836640 is about 19995.9155829384. The cubic root of 399836640 is about 736.7059821727.

The spelling of 399836640 in words is "three hundred ninety-nine million, eight hundred thirty-six thousand, six hundred forty".