261421121132681 has 2 divisors, whose sum is σ = 261421121132682. Its totient is φ = 261421121132680.

The previous prime is 261421121132629. The next prime is 261421121132723. The reversal of 261421121132681 is 186231121124162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 240360217638025 + 21060903494656 = 15503555^2 + 4589216^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261421121132681 is a prime.

It is a super-2 number, since 2×261421121132681² (a number of 30 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (261421121132621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130710560566340 + 130710560566341.

It is an arithmetic number, because the mean of its divisors is an integer number (130710560566341).

Almost surely, 2^{261421121132681} is an apocalyptic number.

It is an amenable number.

261421121132681 is a deficient number, since it is larger than the sum of its proper divisors (1).

261421121132681 is an equidigital number, since it uses as much as digits as its factorization.

261421121132681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 55296, while the sum is 41.

The spelling of 261421121132681 in words is "two hundred sixty-one trillion, four hundred twenty-one billion, one hundred twenty-one million, one hundred thirty-two thousand, six hundred eighty-one".