399881987 has 2 divisors, whose sum is σ = 399881988. Its totient is φ = 399881986.

The previous prime is 399881971. The next prime is 399882053. The reversal of 399881987 is 789188993.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 399881987 - 2⁴ = 399881971 is a prime.

It is not a weakly prime, because it can be changed into another prime (399881387) 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, 199940993 + 199940994.

It is an arithmetic number, because the mean of its divisors is an integer number (199940994).

Almost surely, 2^399881987 is an apocalyptic number.

399881987 is a deficient number, since it is larger than the sum of its proper divisors (1).

399881987 is an equidigital number, since it uses as much as digits as its factorization.

399881987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7838208, while the sum is 62.

The square root of 399881987 is about 19997.0494573575. The cubic root of 399881987 is about 736.7338319993.

The spelling of 399881987 in words is "three hundred ninety-nine million, eight hundred eighty-one thousand, nine hundred eighty-seven".