256921069 has 2 divisors, whose sum is σ = 256921070. Its totient is φ = 256921068.

The previous prime is 256921061. The next prime is 256921099. The reversal of 256921069 is 960129652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 254402500 + 2518569 = 15950^2 + 1587^2 .

It is a cyclic number.

It is not a de Polignac number, because 256921069 - 2³ = 256921061 is a prime.

It is a super-2 number, since 2×256921069² = 132016871392205522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256921061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128460534 + 128460535.

It is an arithmetic number, because the mean of its divisors is an integer number (128460535).

Almost surely, 2^256921069 is an apocalyptic number.

It is an amenable number.

256921069 is a deficient number, since it is larger than the sum of its proper divisors (1).

256921069 is an equidigital number, since it uses as much as digits as its factorization.

256921069 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 58320, while the sum is 40.

The square root of 256921069 is about 16028.7575625811. The cubic root of 256921069 is about 635.7210228081.

The spelling of 256921069 in words is "two hundred fifty-six million, nine hundred twenty-one thousand, sixty-nine".