261646343242237 has 2 divisors, whose sum is σ = 261646343242238. Its totient is φ = 261646343242236.

The previous prime is 261646343242223. The next prime is 261646343242259. The reversal of 261646343242237 is 732242343646162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 246837846233476 + 14808497008761 = 15711074^2 + 3848181^2 .

It is a cyclic number.

It is not a de Polignac number, because 261646343242237 - 2¹⁵ = 261646343209469 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261646343242637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130823171621118 + 130823171621119.

It is an arithmetic number, because the mean of its divisors is an integer number (130823171621119).

Almost surely, 2^{261646343242237} is an apocalyptic number.

It is an amenable number.

261646343242237 is a deficient number, since it is larger than the sum of its proper divisors (1).

261646343242237 is an equidigital number, since it uses as much as digits as its factorization.

261646343242237 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41803776, while the sum is 55.

Adding to 261646343242237 its reverse (732242343646162), we get a palindrome (993888686888399).

The spelling of 261646343242237 in words is "two hundred sixty-one trillion, six hundred forty-six billion, three hundred forty-three million, two hundred forty-two thousand, two hundred thirty-seven".