261287569 has 16 divisors (see below), whose sum is σ = 281413440. Its totient is φ = 241722880.

The previous prime is 261287557. The next prime is 261287573. The reversal of 261287569 is 965782162.

It is a cyclic number.

It is not a de Polignac number, because 261287569 - 2¹⁵ = 261254801 is a prime.

It is a super-2 number, since 2×261287569² = 136542387427859522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261287519) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 396162 + ... + 396820.

It is an arithmetic number, because the mean of its divisors is an integer number (17588340).

Almost surely, 2^261287569 is an apocalyptic number.

It is an amenable number.

261287569 is a deficient number, since it is larger than the sum of its proper divisors (20125871).

261287569 is a wasteful number, since it uses less digits than its factorization.

261287569 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1040.

The product of its digits is 362880, while the sum is 46.

The square root of 261287569 is about 16164.3920083621. The cubic root of 261287569 is about 639.3022742863.

The spelling of 261287569 in words is "two hundred sixty-one million, two hundred eighty-seven thousand, five hundred sixty-nine".