256410512921 has 2 divisors, whose sum is σ = 256410512922. Its totient is φ = 256410512920.

The previous prime is 256410512833. The next prime is 256410512929. The reversal of 256410512921 is 129215014652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 256405513225 + 4999696 = 506365^2 + 2236^2 .

It is a cyclic number.

It is not a de Polignac number, because 256410512921 - 2¹⁰ = 256410511897 is a prime.

It is a super-2 number, since 2×256410512921² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (256410512929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128205256460 + 128205256461.

It is an arithmetic number, because the mean of its divisors is an integer number (128205256461).

Almost surely, 2^256410512921 is an apocalyptic number.

It is an amenable number.

256410512921 is a deficient number, since it is larger than the sum of its proper divisors (1).

256410512921 is an equidigital number, since it uses as much as digits as its factorization.

256410512921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 43200, while the sum is 38.

The spelling of 256410512921 in words is "two hundred fifty-six billion, four hundred ten million, five hundred twelve thousand, nine hundred twenty-one".