399665280 has 256 divisors, whose sum is σ = 1473500160. Its totient is φ = 90255360.

The previous prime is 399665267. The next prime is 399665303. The reversal of 399665280 is 82566993.

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

It is a congruent number.

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, 1760527 + ... + 1760753.

It is an arithmetic number, because the mean of its divisors is an integer number (5755860).

Almost surely, 2^399665280 is an apocalyptic number.

399665280 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 399665280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (736750080).

399665280 is an abundant number, since it is smaller than the sum of its proper divisors (1073834880).

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

399665280 is a wasteful number, since it uses less digits than its factorization.

399665280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 387 (or 375 counting only the distinct ones).

The product of its (nonzero) digits is 699840, while the sum is 48.

The square root of 399665280 is about 19991.6302486816. The cubic root of 399665280 is about 736.6007225379.

The spelling of 399665280 in words is "three hundred ninety-nine million, six hundred sixty-five thousand, two hundred eighty".