261155789 has 2 divisors, whose sum is σ = 261155790. Its totient is φ = 261155788.

The previous prime is 261155761. The next prime is 261155831. The reversal of 261155789 is 987551162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 237468100 + 23687689 = 15410^2 + 4867^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261155789 is a prime.

It is a super-2 number, since 2×261155789² = 136404692256425042, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261155729) 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, 130577894 + 130577895.

It is an arithmetic number, because the mean of its divisors is an integer number (130577895).

Almost surely, 2^261155789 is an apocalyptic number.

It is an amenable number.

261155789 is a deficient number, since it is larger than the sum of its proper divisors (1).

261155789 is an equidigital number, since it uses as much as digits as its factorization.

261155789 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 151200, while the sum is 44.

The square root of 261155789 is about 16160.3152506379. The cubic root of 261155789 is about 639.1947791596.

The spelling of 261155789 in words is "two hundred sixty-one million, one hundred fifty-five thousand, seven hundred eighty-nine".