261440865 has 40 divisors (see below), whose sum is σ = 535613760. Its totient is φ = 119514528.

The previous prime is 261440863. The next prime is 261440869. The reversal of 261440865 is 568044162.

261440865 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 261440865 - 2¹ = 261440863 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261440863) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 43275 + ... + 48944.

It is an arithmetic number, because the mean of its divisors is an integer number (13390344).

Almost surely, 2^261440865 is an apocalyptic number.

It is an amenable number.

261440865 is an abundant number, since it is smaller than the sum of its proper divisors (274172895).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261440865 is an equidigital number, since it uses as much as digits as its factorization.

261440865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92243 (or 92234 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

The square root of 261440865 is about 16169.1330936448. The cubic root of 261440865 is about 639.4272749031.

The spelling of 261440865 in words is "two hundred sixty-one million, four hundred forty thousand, eight hundred sixty-five".