399645663 has 4 divisors (see below), whose sum is σ = 532860888. Its totient is φ = 266430440.

The previous prime is 399645661. The next prime is 399645671. The reversal of 399645663 is 366546993.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 399645663 - 2¹ = 399645661 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399645661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66607608 + ... + 66607613.

It is an arithmetic number, because the mean of its divisors is an integer number (133215222).

Almost surely, 2^399645663 is an apocalyptic number.

399645663 is a deficient number, since it is larger than the sum of its proper divisors (133215225).

399645663 is a wasteful number, since it uses less digits than its factorization.

399645663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133215224.

The product of its digits is 3149280, while the sum is 51.

The square root of 399645663 is about 19991.1396123383. The cubic root of 399645663 is about 736.5886706755.

The spelling of 399645663 in words is "three hundred ninety-nine million, six hundred forty-five thousand, six hundred sixty-three".