261023549 has 2 divisors, whose sum is σ = 261023550. Its totient is φ = 261023548.

The previous prime is 261023537. The next prime is 261023551. The reversal of 261023549 is 945320162.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 258405625 + 2617924 = 16075^2 + 1618^2 .

It is a cyclic number.

It is not a de Polignac number, because 261023549 - 2⁸ = 261023293 is a prime.

Together with 261023551, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261023509) 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, 130511774 + 130511775.

It is an arithmetic number, because the mean of its divisors is an integer number (130511775).

Almost surely, 2^261023549 is an apocalyptic number.

It is an amenable number.

261023549 is a deficient number, since it is larger than the sum of its proper divisors (1).

261023549 is an equidigital number, since it uses as much as digits as its factorization.

261023549 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 261023549 is about 16156.2232282177. The cubic root of 261023549 is about 639.0868724460.

The spelling of 261023549 in words is "two hundred sixty-one million, twenty-three thousand, five hundred forty-nine".