261840365 has 16 divisors (see below), whose sum is σ = 323431680. Its totient is φ = 203411520.

The previous prime is 261840343. The next prime is 261840367. The reversal of 261840365 is 563048162.

It is not a de Polignac number, because 261840365 - 2¹⁸ = 261578221 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261840367) 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, 18662 + ... + 29528.

It is an arithmetic number, because the mean of its divisors is an integer number (20214480).

Almost surely, 2^261840365 is an apocalyptic number.

It is an amenable number.

261840365 is a deficient number, since it is larger than the sum of its proper divisors (61591315).

261840365 is a wasteful number, since it uses less digits than its factorization.

261840365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11012.

The product of its (nonzero) digits is 34560, while the sum is 35.

The square root of 261840365 is about 16181.4821632630. The cubic root of 261840365 is about 639.7528057402.

The spelling of 261840365 in words is "two hundred sixty-one million, eight hundred forty thousand, three hundred sixty-five".