261564130384591 has 2 divisors, whose sum is σ = 261564130384592. Its totient is φ = 261564130384590.

The previous prime is 261564130384567. The next prime is 261564130384691. The reversal of 261564130384591 is 195483031465162.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261564130384591 - 2¹⁷ = 261564130253519 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261564130384391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130782065192295 + 130782065192296.

It is an arithmetic number, because the mean of its divisors is an integer number (130782065192296).

Almost surely, 2^{261564130384591} is an apocalyptic number.

261564130384591 is a deficient number, since it is larger than the sum of its proper divisors (1).

261564130384591 is an equidigital number, since it uses as much as digits as its factorization.

261564130384591 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18662400, while the sum is 58.

The spelling of 261564130384591 in words is "two hundred sixty-one trillion, five hundred sixty-four billion, one hundred thirty million, three hundred eighty-four thousand, five hundred ninety-one".