399731 has 2 divisors, whose sum is σ = 399732. Its totient is φ = 399730.

The previous prime is 399727. The next prime is 399739. The reversal of 399731 is 137993.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (137993) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 399731 - 2² = 399727 is a prime.

It is a super-2 number, since 2×399731² = 319569744722, which contains 22 as substring.

It is a Chen prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 399731.

It is not a weakly prime, because it can be changed into another prime (399739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199865 + 199866.

It is an arithmetic number, because the mean of its divisors is an integer number (199866).

2³⁹⁹⁷³¹ is an apocalyptic number.

399731 is a deficient number, since it is larger than the sum of its proper divisors (1).

399731 is an equidigital number, since it uses as much as digits as its factorization.

399731 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5103, while the sum is 32.

The square root of 399731 is about 632.2428330950. The cubic root of 399731 is about 73.6641095277.

The spelling of 399731 in words is "three hundred ninety-nine thousand, seven hundred thirty-one".