399839989 has 2 divisors, whose sum is σ = 399839990. Its totient is φ = 399839988.

The previous prime is 399839941. The next prime is 399840011. The reversal of 399839989 is 989938993.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 355511025 + 44328964 = 18855^2 + 6658^2 .

It is a cyclic number.

It is not a de Polignac number, because 399839989 - 2¹¹ = 399837941 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399839189) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199919994 + 199919995.

It is an arithmetic number, because the mean of its divisors is an integer number (199919995).

Almost surely, 2^399839989 is an apocalyptic number.

It is an amenable number.

399839989 is a deficient number, since it is larger than the sum of its proper divisors (1).

399839989 is an equidigital number, since it uses as much as digits as its factorization.

399839989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34012224, while the sum is 67.

The square root of 399839989 is about 19995.9993248650. Note that the first 3 decimals coincide. The cubic root of 399839989 is about 736.7080390306.

The spelling of 399839989 in words is "three hundred ninety-nine million, eight hundred thirty-nine thousand, nine hundred eighty-nine".