261244582661 has 2 divisors, whose sum is σ = 261244582662. Its totient is φ = 261244582660.

The previous prime is 261244582637. The next prime is 261244582667. The reversal of 261244582661 is 166285442162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 177246052036 + 83998530625 = 421006^2 + 289825^2 .

It is a cyclic number.

It is not a de Polignac number, because 261244582661 - 2¹⁸ = 261244320517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261244582667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130622291330 + 130622291331.

It is an arithmetic number, because the mean of its divisors is an integer number (130622291331).

Almost surely, 2^261244582661 is an apocalyptic number.

It is an amenable number.

261244582661 is a deficient number, since it is larger than the sum of its proper divisors (1).

261244582661 is an equidigital number, since it uses as much as digits as its factorization.

261244582661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1105920, while the sum is 47.

The spelling of 261244582661 in words is "two hundred sixty-one billion, two hundred forty-four million, five hundred eighty-two thousand, six hundred sixty-one".