261009709 has 2 divisors, whose sum is σ = 261009710. Its totient is φ = 261009708.

The previous prime is 261009673. The next prime is 261009737. The reversal of 261009709 is 907900162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 243453609 + 17556100 = 15603^2 + 4190^2 .

It is a cyclic number.

It is not a de Polignac number, because 261009709 - 2⁹ = 261009197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261009779) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130504854 + 130504855.

It is an arithmetic number, because the mean of its divisors is an integer number (130504855).

Almost surely, 2^261009709 is an apocalyptic number.

It is an amenable number.

261009709 is a deficient number, since it is larger than the sum of its proper divisors (1).

261009709 is an equidigital number, since it uses as much as digits as its factorization.

261009709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6804, while the sum is 34.

The square root of 261009709 is about 16155.7949046155. The cubic root of 261009709 is about 639.0755770173.

The spelling of 261009709 in words is "two hundred sixty-one million, nine thousand, seven hundred nine".