399395891 has 2 divisors, whose sum is σ = 399395892. Its totient is φ = 399395890.

The previous prime is 399395873. The next prime is 399395929. The reversal of 399395891 is 198593993.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 399395891 - 2¹⁴ = 399379507 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (399395791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199697945 + 199697946.

It is an arithmetic number, because the mean of its divisors is an integer number (199697946).

Almost surely, 2^399395891 is an apocalyptic number.

399395891 is a deficient number, since it is larger than the sum of its proper divisors (1).

399395891 is an equidigital number, since it uses as much as digits as its factorization.

399395891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2361960, while the sum is 56.

The square root of 399395891 is about 19984.8915683824. The cubic root of 399395891 is about 736.4351867406.

The spelling of 399395891 in words is "three hundred ninety-nine million, three hundred ninety-five thousand, eight hundred ninety-one".