261577 has 2 divisors, whose sum is σ = 261578. Its totient is φ = 261576.

The previous prime is 261563. The next prime is 261581. The reversal of 261577 is 775162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 219961 + 41616 = 469^2 + 204^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261577 is a prime.

It is not a weakly prime, because it can be changed into another prime (261557) 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, 130788 + 130789.

It is an arithmetic number, because the mean of its divisors is an integer number (130789).

2²⁶¹⁵⁷⁷ is an apocalyptic number.

It is an amenable number.

261577 is a deficient number, since it is larger than the sum of its proper divisors (1).

261577 is an equidigital number, since it uses as much as digits as its factorization.

261577 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2940, while the sum is 28.

The square root of 261577 is about 511.4459893283. The cubic root of 261577 is about 63.9538241141.

It can be divided in two parts, 261 and 577, that added together give a palindrome (838).

The spelling of 261577 in words is "two hundred sixty-one thousand, five hundred seventy-seven".