261655573 has 2 divisors, whose sum is σ = 261655574. Its totient is φ = 261655572.

The previous prime is 261655571. The next prime is 261655607. The reversal of 261655573 is 375556162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 260919409 + 736164 = 16153^2 + 858^2 .

It is a cyclic number.

It is not a de Polignac number, because 261655573 - 2¹ = 261655571 is a prime.

Together with 261655571, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261655571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130827786 + 130827787.

It is an arithmetic number, because the mean of its divisors is an integer number (130827787).

Almost surely, 2^261655573 is an apocalyptic number.

It is an amenable number.

261655573 is a deficient number, since it is larger than the sum of its proper divisors (1).

261655573 is an equidigital number, since it uses as much as digits as its factorization.

261655573 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 189000, while the sum is 40.

The square root of 261655573 is about 16175.7711717247. The cubic root of 261655573 is about 639.6022699705.

The spelling of 261655573 in words is "two hundred sixty-one million, six hundred fifty-five thousand, five hundred seventy-three".