261791569 has 16 divisors (see below), whose sum is σ = 285679744. Its totient is φ = 238464000.

The previous prime is 261791561. The next prime is 261791573. The reversal of 261791569 is 965197162.

It is a cyclic number.

It is not a de Polignac number, because 261791569 - 2³ = 261791561 is a prime.

It is a super-2 number, since 2×261791569² = 137069651198963522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261791561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 378514 + ... + 379204.

It is an arithmetic number, because the mean of its divisors is an integer number (17854984).

Almost surely, 2^261791569 is an apocalyptic number.

It is an amenable number.

261791569 is a deficient number, since it is larger than the sum of its proper divisors (23888175).

261791569 is a wasteful number, since it uses less digits than its factorization.

261791569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1048.

The product of its digits is 204120, while the sum is 46.

The square root of 261791569 is about 16179.9743201280. The cubic root of 261791569 is about 639.7130622915.

The spelling of 261791569 in words is "two hundred sixty-one million, seven hundred ninety-one thousand, five hundred sixty-nine".