256400635646 has 4 divisors (see below), whose sum is σ = 384600953472. Its totient is φ = 128200317822.

The previous prime is 256400635607. The next prime is 256400635709. The reversal of 256400635646 is 646536004652.

It is a happy number.

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

It is a self number, because there is not a number n which added to its sum of digits gives 256400635646.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64100158910 + ... + 64100158913.

It is an arithmetic number, because the mean of its divisors is an integer number (96150238368).

Almost surely, 2^256400635646 is an apocalyptic number.

256400635646 is a deficient number, since it is larger than the sum of its proper divisors (128200317826).

256400635646 is a wasteful number, since it uses less digits than its factorization.

256400635646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128200317825.

The product of its (nonzero) digits is 3110400, while the sum is 47.

The spelling of 256400635646 in words is "two hundred fifty-six billion, four hundred million, six hundred thirty-five thousand, six hundred forty-six".