261509323 has 4 divisors (see below), whose sum is σ = 264447720. Its totient is φ = 258570928.

The previous prime is 261509291. The next prime is 261509371. The reversal of 261509323 is 323905162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 261509323 - 2⁵ = 261509291 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261509393) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1469065 + ... + 1469242.

It is an arithmetic number, because the mean of its divisors is an integer number (66111930).

Almost surely, 2^261509323 is an apocalyptic number.

261509323 is a deficient number, since it is larger than the sum of its proper divisors (2938397).

261509323 is an equidigital number, since it uses as much as digits as its factorization.

261509323 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2938396.

The product of its (nonzero) digits is 9720, while the sum is 31.

The square root of 261509323 is about 16171.2498898508. The cubic root of 261509323 is about 639.4830811396.

The spelling of 261509323 in words is "two hundred sixty-one million, five hundred nine thousand, three hundred twenty-three".