399631680 has 336 divisors, whose sum is σ = 1610953344. Its totient is φ = 89026560.

The previous prime is 399631669. The next prime is 399631681. The reversal of 399631680 is 86136993.

399631680 is a `hidden beast` number, since 3 + 9 + 9 + 631 + 6 + 8 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (336).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399631681) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 866650 + ... + 867110.

It is an arithmetic number, because the mean of its divisors is an integer number (4794504).

Almost surely, 2^399631680 is an apocalyptic number.

399631680 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 399631680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (805476672).

399631680 is an abundant number, since it is smaller than the sum of its proper divisors (1211321664).

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

399631680 is a wasteful number, since it uses less digits than its factorization.

399631680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 534 (or 521 counting only the distinct ones).

The product of its (nonzero) digits is 209952, while the sum is 45.

The square root of 399631680 is about 19990.7898793419. The cubic root of 399631680 is about 736.5800798659.

The spelling of 399631680 in words is "three hundred ninety-nine million, six hundred thirty-one thousand, six hundred eighty".