399989 has 2 divisors, whose sum is σ = 399990. Its totient is φ = 399988.

The previous prime is 399983. The next prime is 400009. The reversal of 399989 is 989993.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 372100 + 27889 = 610^2 + 167^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-399989 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199994 + 199995.

It is an arithmetic number, because the mean of its divisors is an integer number (199995).

2³⁹⁹⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

399989 is a deficient number, since it is larger than the sum of its proper divisors (1).

399989 is an equidigital number, since it uses as much as digits as its factorization.

399989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 157464, while the sum is 47.

The square root of 399989 is about 632.4468357103. The cubic root of 399989 is about 73.6799545608.

The spelling of 399989 in words is "three hundred ninety-nine thousand, nine hundred eighty-nine".