261543072657637 has 2 divisors, whose sum is σ = 261543072657638. Its totient is φ = 261543072657636.

The previous prime is 261543072657617. The next prime is 261543072657653. The reversal of 261543072657637 is 736756270345162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 136802006745121 + 124741065912516 = 11696239^2 + 11168754^2 .

It is a cyclic number.

It is not a de Polignac number, because 261543072657637 - 2²³ = 261543064269029 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261543072657617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130771536328818 + 130771536328819.

It is an arithmetic number, because the mean of its divisors is an integer number (130771536328819).

Almost surely, 2^{261543072657637} is an apocalyptic number.

It is an amenable number.

261543072657637 is a deficient number, since it is larger than the sum of its proper divisors (1).

261543072657637 is an equidigital number, since it uses as much as digits as its factorization.

261543072657637 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 266716800, while the sum is 64.

The spelling of 261543072657637 in words is "two hundred sixty-one trillion, five hundred forty-three billion, seventy-two million, six hundred fifty-seven thousand, six hundred thirty-seven".