261388832644 has 27 divisors (see below), whose sum is σ = 462186923653. Its totient is φ = 129349286000.

The previous prime is 261388832599. The next prime is 261388832659. The reversal of 261388832644 is 446238883162.

The square root of 261388832644 is 511262.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 251139295044 + 10249537600 = 501138^2 + 101240^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 103273659 + ... + 103276189.

Almost surely, 2^261388832644 is an apocalyptic number.

261388832644 is the 511262-nd square number.

It is an amenable number.

261388832644 is a deficient number, since it is larger than the sum of its proper divisors (200798091009).

261388832644 is an frugal number, since it uses more digits than its factorization.

261388832644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5268 (or 2634 counting only the distinct ones).

The product of its digits is 10616832, while the sum is 55.

The spelling of 261388832644 in words is "two hundred sixty-one billion, three hundred eighty-eight million, eight hundred thirty-two thousand, six hundred forty-four".