399784915 has 4 divisors (see below), whose sum is σ = 479741904. Its totient is φ = 319827928.

The previous prime is 399784877. The next prime is 399784933. The reversal of 399784915 is 519487993.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 519487993 = 9293 ⋅55901.

It is a cyclic number.

It is not a de Polignac number, because 399784915 - 2⁹ = 399784403 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39978487 + ... + 39978496.

It is an arithmetic number, because the mean of its divisors is an integer number (119935476).

Almost surely, 2^399784915 is an apocalyptic number.

399784915 is a deficient number, since it is larger than the sum of its proper divisors (79956989).

399784915 is an equidigital number, since it uses as much as digits as its factorization.

399784915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79956988.

The product of its digits is 2449440, while the sum is 55.

The square root of 399784915 is about 19994.6221519688. The cubic root of 399784915 is about 736.6742127312.

The spelling of 399784915 in words is "three hundred ninety-nine million, seven hundred eighty-four thousand, nine hundred fifteen".