399881691 has 20 divisors (see below), whose sum is σ = 651660504. Its totient is φ = 242352000.

The previous prime is 399881689. The next prime is 399881707. The reversal of 399881691 is 196188993.

It is not a de Polignac number, because 399881691 - 2¹ = 399881689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (399881621) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 223510 + ... + 225291.

Almost surely, 2^399881691 is an apocalyptic number.

399881691 is a deficient number, since it is larger than the sum of its proper divisors (251778813).

399881691 is a wasteful number, since it uses less digits than its factorization.

399881691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 448824 (or 448815 counting only the distinct ones).

The product of its digits is 839808, while the sum is 54.

The square root of 399881691 is about 19997.0420562642. The cubic root of 399881691 is about 736.7336502179.

The spelling of 399881691 in words is "three hundred ninety-nine million, eight hundred eighty-one thousand, six hundred ninety-one".