399720971665 has 16 divisors (see below), whose sum is σ = 488996928000. Its totient is φ = 313609937472.

The previous prime is 399720971659. The next prime is 399720971681. The reversal of 399720971665 is 566179027993.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-399720971665 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 399720971597 and 399720971606.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3336957 + ... + 3454666.

It is an arithmetic number, because the mean of its divisors is an integer number (30562308000).

Almost surely, 2^399720971665 is an apocalyptic number.

It is an amenable number.

399720971665 is a deficient number, since it is larger than the sum of its proper divisors (89275956335).

399720971665 is a wasteful number, since it uses less digits than its factorization.

399720971665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6791856.

The product of its (nonzero) digits is 38578680, while the sum is 64.

The spelling of 399720971665 in words is "three hundred ninety-nine billion, seven hundred twenty million, nine hundred seventy-one thousand, six hundred sixty-five".