261970409 has 2 divisors, whose sum is σ = 261970410. Its totient is φ = 261970408.

The previous prime is 261970363. The next prime is 261970411. The reversal of 261970409 is 904079162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 257442025 + 4528384 = 16045^2 + 2128^2 .

It is a cyclic number.

It is not a de Polignac number, because 261970409 - 2²⁰ = 260921833 is a prime.

Together with 261970411, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (261970439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130985204 + 130985205.

It is an arithmetic number, because the mean of its divisors is an integer number (130985205).

Almost surely, 2^261970409 is an apocalyptic number.

It is an amenable number.

261970409 is a deficient number, since it is larger than the sum of its proper divisors (1).

261970409 is an equidigital number, since it uses as much as digits as its factorization.

261970409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27216, while the sum is 38.

The square root of 261970409 is about 16185.4999613852. The cubic root of 261970409 is about 639.8587000885.

The spelling of 261970409 in words is "two hundred sixty-one million, nine hundred seventy thousand, four hundred nine".