256561636426 has 8 divisors (see below), whose sum is σ = 391151347524. Its totient is φ = 126177853920.

The previous prime is 256561636423. The next prime is 256561636427. The reversal of 256561636426 is 624636165652.

It can be written as a sum of positive squares in 2 ways, for example, as 240899364225 + 15662272201 = 490815^2 + 125149^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (256561636423) 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, 1051481995 + ... + 1051482238.

Almost surely, 2^256561636426 is an apocalyptic number.

256561636426 is a deficient number, since it is larger than the sum of its proper divisors (134589711098).

256561636426 is a wasteful number, since it uses less digits than its factorization.

256561636426 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2102964296.

The product of its digits is 9331200, while the sum is 52.

The spelling of 256561636426 in words is "two hundred fifty-six billion, five hundred sixty-one million, six hundred thirty-six thousand, four hundred twenty-six".