261236287383509 has 2 divisors, whose sum is σ = 261236287383510. Its totient is φ = 261236287383508.

The previous prime is 261236287383497. The next prime is 261236287383529. The reversal of 261236287383509 is 905383782632162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 170470233780625 + 90766053602884 = 13056425^2 + 9527122^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261236287383509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261236287383529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130618143691754 + 130618143691755.

It is an arithmetic number, because the mean of its divisors is an integer number (130618143691755).

Almost surely, 2^{261236287383509} is an apocalyptic number.

It is an amenable number.

261236287383509 is a deficient number, since it is larger than the sum of its proper divisors (1).

261236287383509 is an equidigital number, since it uses as much as digits as its factorization.

261236287383509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 156764160, while the sum is 65.

The spelling of 261236287383509 in words is "two hundred sixty-one trillion, two hundred thirty-six billion, two hundred eighty-seven million, three hundred eighty-three thousand, five hundred nine".