399855901 has 2 divisors, whose sum is σ = 399855902. Its totient is φ = 399855900.

The previous prime is 399855889. The next prime is 399855913. The reversal of 399855901 is 109558993.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (399855889) and next prime (399855913).

It can be written as a sum of positive squares in only one way, i.e., 335439225 + 64416676 = 18315^2 + 8026^2 .

It is an emirp because it is prime and its reverse (109558993) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 399855901 - 2⁷ = 399855773 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399855971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199927950 + 199927951.

It is an arithmetic number, because the mean of its divisors is an integer number (199927951).

Almost surely, 2^399855901 is an apocalyptic number.

It is an amenable number.

399855901 is a deficient number, since it is larger than the sum of its proper divisors (1).

399855901 is an equidigital number, since it uses as much as digits as its factorization.

399855901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 437400, while the sum is 49.

The square root of 399855901 is about 19996.3972004959. The cubic root of 399855901 is about 736.7178115589.

The spelling of 399855901 in words is "three hundred ninety-nine million, eight hundred fifty-five thousand, nine hundred one".