399436805 has 4 divisors (see below), whose sum is σ = 479324172. Its totient is φ = 319549440.

The previous prime is 399436787. The next prime is 399436819. The reversal of 399436805 is 508634993.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 508634993 = 977 ⋅520609.

It can be written as a sum of positive squares in 2 ways, for example, as 211033729 + 188403076 = 14527^2 + 13726^2 .

It is not a de Polignac number, because 399436805 - 2¹⁰ = 399435781 is a prime.

It is a super-2 number, since 2×399436805² = 319099522377216050, which contains 22 as substring.

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 399436805.

It is a congruent 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, 39943676 + ... + 39943685.

It is an arithmetic number, because the mean of its divisors is an integer number (119831043).

Almost surely, 2^399436805 is an apocalyptic number.

It is an amenable number.

399436805 is a deficient number, since it is larger than the sum of its proper divisors (79887367).

399436805 is an equidigital number, since it uses as much as digits as its factorization.

399436805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79887366.

The product of its (nonzero) digits is 699840, while the sum is 47.

The square root of 399436805 is about 19985.9151654359. The cubic root of 399436805 is about 736.4603326181.

The spelling of 399436805 in words is "three hundred ninety-nine million, four hundred thirty-six thousand, eight hundred five".