261010209 has 4 divisors (see below), whose sum is σ = 348013616. Its totient is φ = 174006804.

The previous prime is 261010193. The next prime is 261010229. The reversal of 261010209 is 902010162.

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 not a de Polignac number, because 261010209 - 2⁴ = 261010193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261010229) 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, 43501699 + ... + 43501704.

It is an arithmetic number, because the mean of its divisors is an integer number (87003404).

Almost surely, 2^261010209 is an apocalyptic number.

It is an amenable number.

261010209 is a deficient number, since it is larger than the sum of its proper divisors (87003407).

261010209 is an equidigital number, since it uses as much as digits as its factorization.

261010209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87003406.

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 261010209 is about 16155.8103789318. The cubic root of 261010209 is about 639.0759850961.

The spelling of 261010209 in words is "two hundred sixty-one million, ten thousand, two hundred nine".