399969 has 12 divisors (see below), whose sum is σ = 608400. Its totient is φ = 252504.

The previous prime is 399953. The next prime is 399979. The reversal of 399969 is 969993.

399969 is nontrivially palindromic in base 8.

It is not a de Polignac number, because 399969 - 2⁴ = 399953 is a prime.

It is a super-2 number, since 2×399969² = 319950401922, which contains 22 as substring.

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

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 999 + ... + 1340.

It is an arithmetic number, because the mean of its divisors is an integer number (50700).

2³⁹⁹⁹⁶⁹ is an apocalyptic number.

It is an amenable number.

399969 is a deficient number, since it is larger than the sum of its proper divisors (208431).

399969 is a wasteful number, since it uses less digits than its factorization.

399969 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2364 (or 2361 counting only the distinct ones).

The product of its digits is 118098, while the sum is 45.

The square root of 399969 is about 632.4310239070. The cubic root of 399969 is about 73.6787265074.

The spelling of 399969 in words is "three hundred ninety-nine thousand, nine hundred sixty-nine".