399287891 has 12 divisors (see below), whose sum is σ = 425177808. Its totient is φ = 374896512.

The previous prime is 399287839. The next prime is 399287899. The reversal of 399287891 is 198782993.

It is not a de Polignac number, because 399287891 - 2⁶ = 399287827 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (399287899) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 139325 + ... + 142161.

It is an arithmetic number, because the mean of its divisors is an integer number (35431484).

Almost surely, 2^399287891 is an apocalyptic number.

399287891 is a deficient number, since it is larger than the sum of its proper divisors (25889917).

399287891 is a wasteful number, since it uses less digits than its factorization.

399287891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3358 (or 3341 counting only the distinct ones).

The product of its digits is 1959552, while the sum is 56.

The square root of 399287891 is about 19982.1893445138. The cubic root of 399287891 is about 736.3688013387.

The spelling of 399287891 in words is "three hundred ninety-nine million, two hundred eighty-seven thousand, eight hundred ninety-one".