399825665 has 4 divisors (see below), whose sum is σ = 479790804. Its totient is φ = 319860528.

The previous prime is 399825623. The next prime is 399825667. The reversal of 399825665 is 566528993.

399825665 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 227376241 + 172449424 = 15079^2 + 13132^2 .

It is a cyclic number.

It is not a de Polignac number, because 399825665 - 2¹⁰ = 399824641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (399825667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39982562 + ... + 39982571.

It is an arithmetic number, because the mean of its divisors is an integer number (119947701).

Almost surely, 2^399825665 is an apocalyptic number.

It is an amenable number.

399825665 is a deficient number, since it is larger than the sum of its proper divisors (79965139).

399825665 is an equidigital number, since it uses as much as digits as its factorization.

399825665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79965138.

The product of its digits is 3499200, while the sum is 53.

The square root of 399825665 is about 19995.6411500107. The cubic root of 399825665 is about 736.6992415680.

The spelling of 399825665 in words is "three hundred ninety-nine million, eight hundred twenty-five thousand, six hundred sixty-five".