261388832643 has 12 divisors (see below), whose sum is σ = 377569032048. Its totient is φ = 174255813360.

The previous prime is 261388832599. The next prime is 261388832659. The reversal of 261388832643 is 346238883162.

It is a Cunningham number, because it is equal to 511262²-1.

It is not a de Polignac number, because 261388832643 - 2²⁵ = 261355278211 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261388832643.

It is not an unprimeable number, because it can be changed into a prime (261388832143) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 255633 + ... + 766893.

It is an arithmetic number, because the mean of its divisors is an integer number (31464086004).

Almost surely, 2^261388832643 is an apocalyptic number.

261388832643 is a deficient number, since it is larger than the sum of its proper divisors (116180199405).

261388832643 is a wasteful number, since it uses less digits than its factorization.

261388832643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 568074 (or 568071 counting only the distinct ones).

The product of its digits is 7962624, while the sum is 54.

The spelling of 261388832643 in words is "two hundred sixty-one billion, three hundred eighty-eight million, eight hundred thirty-two thousand, six hundred forty-three".