261588262849 has 3 divisors (see below), whose sum is σ = 261588774307. Its totient is φ = 261587751392.

The previous prime is 261588262847. The next prime is 261588262913. The reversal of 261588262849 is 948262885162.

The square root of 261588262849 is 511457.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 101133540225 + 160454722624 = 318015^2 + 400568^2 .

It is not a de Polignac number, because 261588262849 - 2¹ = 261588262847 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261588262843) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 255729 + ... + 767185.

Almost surely, 2^261588262849 is an apocalyptic number.

261588262849 is the 511457-th square number.

261588262849 is the 255729-th centered octagonal number.

It is an amenable number.

261588262849 is a deficient number, since it is larger than the sum of its proper divisors (511458).

261588262849 is an frugal number, since it uses more digits than its factorization.

261588262849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1022914 (or 511457 counting only the distinct ones).

The product of its digits is 26542080, while the sum is 61.

The spelling of 261588262849 in words is "two hundred sixty-one billion, five hundred eighty-eight million, two hundred sixty-two thousand, eight hundred forty-nine".