399157987 has 2 divisors, whose sum is σ = 399157988. Its totient is φ = 399157986.

The previous prime is 399157933. The next prime is 399157991. The reversal of 399157987 is 789751993.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 399157987 - 2¹⁵ = 399125219 is a prime.

It is not a weakly prime, because it can be changed into another prime (399157907) 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, 199578993 + 199578994.

It is an arithmetic number, because the mean of its divisors is an integer number (199578994).

Almost surely, 2^399157987 is an apocalyptic number.

399157987 is a deficient number, since it is larger than the sum of its proper divisors (1).

399157987 is an equidigital number, since it uses as much as digits as its factorization.

399157987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4286520, while the sum is 58.

The square root of 399157987 is about 19978.9385854204. The cubic root of 399157987 is about 736.2889361333.

The spelling of 399157987 in words is "three hundred ninety-nine million, one hundred fifty-seven thousand, nine hundred eighty-seven".