256561536 has 128 divisors (see below), whose sum is σ = 849749760. Its totient is φ = 66631680.

The previous prime is 256561507. The next prime is 256561537. The reversal of 256561536 is 635165652.

It is a tau number, because it is divible by the number of its divisors (128).

It is a junction number, because it is equal to n+sod(n) for n = 256561494 and 256561503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256561537) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25230 + ... + 33906.

It is an arithmetic number, because the mean of its divisors is an integer number (6638670).

Almost surely, 2^256561536 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 256561536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (424874880).

256561536 is an abundant number, since it is smaller than the sum of its proper divisors (593188224).

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

256561536 is a wasteful number, since it uses less digits than its factorization.

256561536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8712 (or 8700 counting only the distinct ones).

The product of its digits is 162000, while the sum is 39.

The square root of 256561536 is about 16017.5383876550. The cubic root of 256561536 is about 635.4243436418.

The spelling of 256561536 in words is "two hundred fifty-six million, five hundred sixty-one thousand, five hundred thirty-six".