261313009 has 2 divisors, whose sum is σ = 261313010. Its totient is φ = 261313008.

The previous prime is 261313007. The next prime is 261313037. The reversal of 261313009 is 900313162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 213744400 + 47568609 = 14620^2 + 6897^2 .

It is a cyclic number.

It is not a de Polignac number, because 261313009 - 2¹ = 261313007 is a prime.

Together with 261313007, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (261313007) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130656504 + 130656505.

It is an arithmetic number, because the mean of its divisors is an integer number (130656505).

Almost surely, 2^261313009 is an apocalyptic number.

It is an amenable number.

261313009 is a deficient number, since it is larger than the sum of its proper divisors (1).

261313009 is an equidigital number, since it uses as much as digits as its factorization.

261313009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 972, while the sum is 25.

The square root of 261313009 is about 16165.1789040518. The cubic root of 261313009 is about 639.3230219528.

The spelling of 261313009 in words is "two hundred sixty-one million, three hundred thirteen thousand, nine".