399431 has 4 divisors (see below), whose sum is σ = 403272. Its totient is φ = 395592.

The previous prime is 399409. The next prime is 399433. The reversal of 399431 is 134993.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 134993 = 61 ⋅2213.

It is a cyclic number.

It is not a de Polignac number, because 399431 - 2¹⁰ = 398407 is a prime.

It is a super-2 number, since 2×399431² = 319090247522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 399394 and 399403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399433) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1760 + ... + 1973.

It is an arithmetic number, because the mean of its divisors is an integer number (100818).

2³⁹⁹⁴³¹ is an apocalyptic number.

399431 is a deficient number, since it is larger than the sum of its proper divisors (3841).

399431 is a wasteful number, since it uses less digits than its factorization.

399431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3840.

The product of its digits is 2916, while the sum is 29.

The square root of 399431 is about 632.0055379504. The cubic root of 399431 is about 73.6456764951.

The spelling of 399431 in words is "three hundred ninety-nine thousand, four hundred thirty-one".