261197549 has 2 divisors, whose sum is σ = 261197550. Its totient is φ = 261197548.

The previous prime is 261197527. The next prime is 261197611. The reversal of 261197549 is 945791162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 207072100 + 54125449 = 14390^2 + 7357^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261197549 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261197509) 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, 130598774 + 130598775.

It is an arithmetic number, because the mean of its divisors is an integer number (130598775).

Almost surely, 2^261197549 is an apocalyptic number.

It is an amenable number.

261197549 is a deficient number, since it is larger than the sum of its proper divisors (1).

261197549 is an equidigital number, since it uses as much as digits as its factorization.

261197549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 136080, while the sum is 44.

The square root of 261197549 is about 16161.6072529931. The cubic root of 261197549 is about 639.2288473958.

The spelling of 261197549 in words is "two hundred sixty-one million, one hundred ninety-seven thousand, five hundred forty-nine".