261891263 has 2 divisors, whose sum is σ = 261891264. Its totient is φ = 261891262.

The previous prime is 261891233. The next prime is 261891281. The reversal of 261891263 is 362198162.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261891263 - 2²⁴ = 245114047 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261891233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130945631 + 130945632.

It is an arithmetic number, because the mean of its divisors is an integer number (130945632).

Almost surely, 2^261891263 is an apocalyptic number.

261891263 is a deficient number, since it is larger than the sum of its proper divisors (1).

261891263 is an equidigital number, since it uses as much as digits as its factorization.

261891263 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 38.

The square root of 261891263 is about 16183.0548105109. The cubic root of 261891263 is about 639.7942559684.

The spelling of 261891263 in words is "two hundred sixty-one million, eight hundred ninety-one thousand, two hundred sixty-three".