261719009 has 2 divisors, whose sum is σ = 261719010. Its totient is φ = 261719008.

The previous prime is 261718999. The next prime is 261719033. The reversal of 261719009 is 900917162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 159769600 + 101949409 = 12640^2 + 10097^2 .

It is a cyclic number.

It is not a de Polignac number, because 261719009 - 2⁸ = 261718753 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261719009.

It is not a weakly prime, because it can be changed into another prime (261719039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130859504 + 130859505.

It is an arithmetic number, because the mean of its divisors is an integer number (130859505).

Almost surely, 2^261719009 is an apocalyptic number.

It is an amenable number.

261719009 is a deficient number, since it is larger than the sum of its proper divisors (1).

261719009 is an equidigital number, since it uses as much as digits as its factorization.

261719009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6804, while the sum is 35.

The square root of 261719009 is about 16177.7318867634. The cubic root of 261719009 is about 639.6539543669.

The spelling of 261719009 in words is "two hundred sixty-one million, seven hundred nineteen thousand, nine".