399280 has 80 divisors (see below), whose sum is σ = 1142784. Its totient is φ = 126720.

The previous prime is 399277. The next prime is 399281. The reversal of 399280 is 82993.

It is a happy number.

399280 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (31).

It is not an unprimeable number, because it can be changed into a prime (399281) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12865 + ... + 12895.

2³⁹⁹²⁸⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 399280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (571392).

399280 is an abundant number, since it is smaller than the sum of its proper divisors (743504).

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

399280 is a wasteful number, since it uses less digits than its factorization.

399280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74 (or 68 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 399280 is about 631.8860656796. The cubic root of 399280 is about 73.6363950432.

399280 divided by its sum of digits (31) gives a triangular number (12880 = T₁₆₀).

The spelling of 399280 in words is "three hundred ninety-nine thousand, two hundred eighty".