261155831 has 2 divisors, whose sum is σ = 261155832. Its totient is φ = 261155830.

The previous prime is 261155789. The next prime is 261155903. The reversal of 261155831 is 138551162.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261155831 - 2¹⁰ = 261154807 is a prime.

It is a super-2 number, since 2×261155831² = 136404736130601122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261151831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130577915 + 130577916.

It is an arithmetic number, because the mean of its divisors is an integer number (130577916).

Almost surely, 2^261155831 is an apocalyptic number.

261155831 is a deficient number, since it is larger than the sum of its proper divisors (1).

261155831 is an equidigital number, since it uses as much as digits as its factorization.

261155831 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7200, while the sum is 32.

The square root of 261155831 is about 16160.3165501175. The cubic root of 261155831 is about 639.1948134255.

The spelling of 261155831 in words is "two hundred sixty-one million, one hundred fifty-five thousand, eight hundred thirty-one".