399424 has 21 divisors (see below), whose sum is σ = 802767. Its totient is φ = 197184.

The previous prime is 399409. The next prime is 399433. The reversal of 399424 is 424993.

The square root of 399424 is 632.

It is a perfect power (a square), and thus also a powerful number.

It is a Duffinian number.

Its product of digits (7776) is a multiple of the sum of its prime divisors (81).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 5017 + ... + 5095.

It is an arithmetic number, because the mean of its divisors is an integer number (38227).

2³⁹⁹⁴²⁴ is an apocalyptic number.

399424 is the 632-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 399424

399424 is an abundant number, since it is smaller than the sum of its proper divisors (403343).

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

399424 is an frugal number, since it uses more digits than its factorization.

399424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170 (or 81 counting only the distinct ones).

The product of its digits is 7776, while the sum is 31.

The cubic root of 399424 is about 73.6452462808.

The spelling of 399424 in words is "three hundred ninety-nine thousand, four hundred twenty-four".