399469991 has 8 divisors (see below), whose sum is σ = 403630080. Its totient is φ = 395326008.

The previous prime is 399469969. The next prime is 399469997. The reversal of 399469991 is 199964993.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 399469991 - 2¹⁸ = 399207847 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 399469991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399469997) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49460 + ... + 56966.

It is an arithmetic number, because the mean of its divisors is an integer number (50453760).

Almost surely, 2^399469991 is an apocalyptic number.

399469991 is a deficient number, since it is larger than the sum of its proper divisors (4160089).

399469991 is a wasteful number, since it uses less digits than its factorization.

399469991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8053.

The product of its digits is 4251528, while the sum is 59.

The square root of 399469991 is about 19986.7453828781. The cubic root of 399469991 is about 736.4807275805.

The spelling of 399469991 in words is "three hundred ninety-nine million, four hundred sixty-nine thousand, nine hundred ninety-one".