261324209 has 2 divisors, whose sum is σ = 261324210. Its totient is φ = 261324208.

The previous prime is 261324149. The next prime is 261324223. The reversal of 261324209 is 902423162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 189667984 + 71656225 = 13772^2 + 8465^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261324209 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (261321209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130662104 + 130662105.

It is an arithmetic number, because the mean of its divisors is an integer number (130662105).

Almost surely, 2^261324209 is an apocalyptic number.

It is an amenable number.

261324209 is a deficient number, since it is larger than the sum of its proper divisors (1).

261324209 is an equidigital number, since it uses as much as digits as its factorization.

261324209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 261324209 is about 16165.5253239726. The cubic root of 261324209 is about 639.3321557187.

The spelling of 261324209 in words is "two hundred sixty-one million, three hundred twenty-four thousand, two hundred nine".