256521125647 has 2 divisors, whose sum is σ = 256521125648. Its totient is φ = 256521125646.

The previous prime is 256521125617. The next prime is 256521125681. The reversal of 256521125647 is 746521125652.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 256521125647 - 2¹⁵ = 256521092879 is a prime.

It is a super-2 number, since 2×256521125647² (a number of 24 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 256521125597 and 256521125606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256521125617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128260562823 + 128260562824.

It is an arithmetic number, because the mean of its divisors is an integer number (128260562824).

Almost surely, 2^256521125647 is an apocalyptic number.

256521125647 is a deficient number, since it is larger than the sum of its proper divisors (1).

256521125647 is an equidigital number, since it uses as much as digits as its factorization.

256521125647 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1008000, while the sum is 46.

The spelling of 256521125647 in words is "two hundred fifty-six billion, five hundred twenty-one million, one hundred twenty-five thousand, six hundred forty-seven".