261543742517563 has 48 divisors (see below), whose sum is σ = 305795986594560. Its totient is φ = 223025219743040.

The previous prime is 261543742517513. The next prime is 261543742517581. The reversal of 261543742517563 is 365715247345162.

It is a de Polignac number, because none of the positive numbers 2^k-261543742517563 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261543742517513) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 291452520 + ... + 292348522.

It is an arithmetic number, because the mean of its divisors is an integer number (6370749720720).

Almost surely, 2^{261543742517563} is an apocalyptic number.

261543742517563 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

261543742517563 is a deficient number, since it is larger than the sum of its proper divisors (44252244076997).

261543742517563 is a wasteful number, since it uses less digits than its factorization.

261543742517563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 898080 (or 898069 counting only the distinct ones).

The product of its digits is 127008000, while the sum is 61.

The spelling of 261543742517563 in words is "two hundred sixty-one trillion, five hundred forty-three billion, seven hundred forty-two million, five hundred seventeen thousand, five hundred sixty-three".