399972 has 12 divisors (see below), whose sum is σ = 933296. Its totient is φ = 133320.

The previous prime is 399953. The next prime is 399979. The reversal of 399972 is 279993.

It is a tau number, because it is divible by the number of its divisors (12).

It is a self number, because there is not a number n which added to its sum of digits gives 399972.

It is not an unprimeable number, because it can be changed into a prime (399979) by changing a digit.

399972 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16654 + ... + 16677.

2³⁹⁹⁹⁷² is an apocalyptic number.

It is an amenable number.

399972 is an abundant number, since it is smaller than the sum of its proper divisors (533324).

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

399972 is a wasteful number, since it uses less digits than its factorization.

399972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33338 (or 33336 counting only the distinct ones).

The product of its digits is 30618, while the sum is 39.

The square root of 399972 is about 632.4333957027. The cubic root of 399972 is about 73.6789107180.

It can be divided in two parts, 39 and 9972, that added together give a triangular number (10011 = T₁₄₁).

The spelling of 399972 in words is "three hundred ninety-nine thousand, nine hundred seventy-two".