261442591 has 2 divisors, whose sum is σ = 261442592. Its totient is φ = 261442590.

The previous prime is 261442589. The next prime is 261442637. The reversal of 261442591 is 195244162.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261442591 - 2¹ = 261442589 is a prime.

Together with 261442589, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261442091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130721295 + 130721296.

It is an arithmetic number, because the mean of its divisors is an integer number (130721296).

Almost surely, 2^261442591 is an apocalyptic number.

261442591 is a deficient number, since it is larger than the sum of its proper divisors (1).

261442591 is an equidigital number, since it uses as much as digits as its factorization.

261442591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17280, while the sum is 34.

The square root of 261442591 is about 16169.1864668573. The cubic root of 261442591 is about 639.4286820397.

The spelling of 261442591 in words is "two hundred sixty-one million, four hundred forty-two thousand, five hundred ninety-one".