261921839089 has 9 divisors (see below), whose sum is σ = 267637793227. Its totient is φ = 256325491984.

The previous prime is 261921839087. The next prime is 261921839111. The reversal of 261921839089 is 980938129162.

The square root of 261921839089 is 511783.

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., 8067093489 + 253854745600 = 89817^2 + 503840^2 .

It is not a de Polignac number, because 261921839089 - 2¹ = 261921839087 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261921839083) by changing a digit.

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, 24048357 + ... + 24059245.

Almost surely, 2^261921839089 is an apocalyptic number.

261921839089 is the 511783-rd square number.

261921839089 is the 255892-nd centered octagonal number.

It is an amenable number.

261921839089 is a deficient number, since it is larger than the sum of its proper divisors (5715954138).

261921839089 is an frugal number, since it uses more digits than its factorization.

261921839089 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21872 (or 10936 counting only the distinct ones).

The product of its (nonzero) digits is 3359232, while the sum is 58.

The spelling of 261921839089 in words is "two hundred sixty-one billion, nine hundred twenty-one million, eight hundred thirty-nine thousand, eighty-nine".