399956865520 has 20 divisors (see below), whose sum is σ = 929899712520. Its totient is φ = 159982746176.

The previous prime is 399956865493. The next prime is 399956865527. The reversal of 399956865520 is 25568659993.

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399956865527) 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, 2499730330 + ... + 2499730489.

It is an arithmetic number, because the mean of its divisors is an integer number (46494985626).

Almost surely, 2^399956865520 is an apocalyptic number.

It is an amenable number.

399956865520 is an abundant number, since it is smaller than the sum of its proper divisors (529942847000).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

399956865520 is a wasteful number, since it uses less digits than its factorization.

399956865520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4999460832 (or 4999460826 counting only the distinct ones).

The product of its (nonzero) digits is 157464000, while the sum is 67.

The spelling of 399956865520 in words is "three hundred ninety-nine billion, nine hundred fifty-six million, eight hundred sixty-five thousand, five hundred twenty".