261685289 has 4 divisors (see below), whose sum is σ = 262610256. Its totient is φ = 260760324.

The previous prime is 261685279. The next prime is 261685351. The reversal of 261685289 is 982586162.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 261685289 - 2²⁴ = 244908073 is a prime.

It is a super-3 number, since 3×261685289³ (a number of 26 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261685219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 462059 + ... + 462624.

It is an arithmetic number, because the mean of its divisors is an integer number (65652564).

Almost surely, 2^261685289 is an apocalyptic number.

It is an amenable number.

261685289 is a deficient number, since it is larger than the sum of its proper divisors (924967).

261685289 is an equidigital number, since it uses as much as digits as its factorization.

261685289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 924966.

The product of its digits is 414720, while the sum is 47.

The square root of 261685289 is about 16176.6896799067. The cubic root of 261685289 is about 639.6264820818.

The spelling of 261685289 in words is "two hundred sixty-one million, six hundred eighty-five thousand, two hundred eighty-nine".