256621604721061 has 2 divisors, whose sum is σ = 256621604721062. Its totient is φ = 256621604721060.

The previous prime is 256621604721029. The next prime is 256621604721161. The reversal of 256621604721061 is 160127406126652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 198581814712836 + 58039790008225 = 14091906^2 + 7618385^2 .

It is a cyclic number.

It is not a de Polignac number, because 256621604721061 - 2⁵ = 256621604721029 is a prime.

It is a super-2 number, since 2×256621604721061² (a number of 30 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 256621604720996 and 256621604721014.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256621604721161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128310802360530 + 128310802360531.

It is an arithmetic number, because the mean of its divisors is an integer number (128310802360531).

Almost surely, 2^{256621604721061} is an apocalyptic number.

It is an amenable number.

256621604721061 is a deficient number, since it is larger than the sum of its proper divisors (1).

256621604721061 is an equidigital number, since it uses as much as digits as its factorization.

256621604721061 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1451520, while the sum is 49.

The spelling of 256621604721061 in words is "two hundred fifty-six trillion, six hundred twenty-one billion, six hundred four million, seven hundred twenty-one thousand, sixty-one".