261123256489 has 2 divisors, whose sum is σ = 261123256490. Its totient is φ = 261123256488.

The previous prime is 261123256487. The next prime is 261123256501. The reversal of 261123256489 is 984652321162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 238827690000 + 22295566489 = 488700^2 + 149317^2 .

It is a cyclic number.

It is not a de Polignac number, because 261123256489 - 2¹ = 261123256487 is a prime.

Together with 261123256487, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (261123256487) 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, 130561628244 + 130561628245.

It is an arithmetic number, because the mean of its divisors is an integer number (130561628245).

Almost surely, 2^261123256489 is an apocalyptic number.

It is an amenable number.

261123256489 is a deficient number, since it is larger than the sum of its proper divisors (1).

261123256489 is an equidigital number, since it uses as much as digits as its factorization.

261123256489 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1244160, while the sum is 49.

The spelling of 261123256489 in words is "two hundred sixty-one billion, one hundred twenty-three million, two hundred fifty-six thousand, four hundred eighty-nine".