261321559 has 2 divisors, whose sum is σ = 261321560. Its totient is φ = 261321558.

The previous prime is 261321553. The next prime is 261321587. The reversal of 261321559 is 955123162.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261321559 - 2¹¹ = 261319511 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261321553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130660779 + 130660780.

It is an arithmetic number, because the mean of its divisors is an integer number (130660780).

Almost surely, 2^261321559 is an apocalyptic number.

261321559 is a deficient number, since it is larger than the sum of its proper divisors (1).

261321559 is an equidigital number, since it uses as much as digits as its factorization.

261321559 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16200, while the sum is 34.

The square root of 261321559 is about 16165.4433592154. The cubic root of 261321559 is about 639.3299946281.

The spelling of 261321559 in words is "two hundred sixty-one million, three hundred twenty-one thousand, five hundred fifty-nine".