261549797 has 2 divisors, whose sum is σ = 261549798. Its totient is φ = 261549796.

The previous prime is 261549653. The next prime is 261549817. The reversal of 261549797 is 797945162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 255552196 + 5997601 = 15986^2 + 2449^2 .

It is a cyclic number.

It is not a de Polignac number, because 261549797 - 2¹⁶ = 261484261 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261549397) 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, 130774898 + 130774899.

It is an arithmetic number, because the mean of its divisors is an integer number (130774899).

Almost surely, 2^261549797 is an apocalyptic number.

It is an amenable number.

261549797 is a deficient number, since it is larger than the sum of its proper divisors (1).

261549797 is an equidigital number, since it uses as much as digits as its factorization.

261549797 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 952560, while the sum is 50.

The square root of 261549797 is about 16172.5012598546. The cubic root of 261549797 is about 639.5160705346.

The spelling of 261549797 in words is "two hundred sixty-one million, five hundred forty-nine thousand, seven hundred ninety-seven".