256617649 has 2 divisors, whose sum is σ = 256617650. Its totient is φ = 256617648.

The previous prime is 256617623. The next prime is 256617653. The reversal of 256617649 is 946716652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 235162225 + 21455424 = 15335^2 + 4632^2 .

It is a cyclic number.

It is not a de Polignac number, because 256617649 - 2⁵ = 256617617 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 256617599 and 256617608.

It is not a weakly prime, because it can be changed into another prime (256627649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128308824 + 128308825.

It is an arithmetic number, because the mean of its divisors is an integer number (128308825).

Almost surely, 2^256617649 is an apocalyptic number.

It is an amenable number.

256617649 is a deficient number, since it is larger than the sum of its proper divisors (1).

256617649 is an equidigital number, since it uses as much as digits as its factorization.

256617649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 544320, while the sum is 46.

The square root of 256617649 is about 16019.2899031137. The cubic root of 256617649 is about 635.4706651698.

The spelling of 256617649 in words is "two hundred fifty-six million, six hundred seventeen thousand, six hundred forty-nine".