261534263432551 has 2 divisors, whose sum is σ = 261534263432552. Its totient is φ = 261534263432550.

The previous prime is 261534263432543. The next prime is 261534263432657. The reversal of 261534263432551 is 155234362435162.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261534263432551 - 2³ = 261534263432543 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261534263432951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130767131716275 + 130767131716276.

It is an arithmetic number, because the mean of its divisors is an integer number (130767131716276).

Almost surely, 2^{261534263432551} is an apocalyptic number.

261534263432551 is a deficient number, since it is larger than the sum of its proper divisors (1).

261534263432551 is an equidigital number, since it uses as much as digits as its factorization.

261534263432551 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15552000, while the sum is 52.

The spelling of 261534263432551 in words is "two hundred sixty-one trillion, five hundred thirty-four billion, two hundred sixty-three million, four hundred thirty-two thousand, five hundred fifty-one".