261695557 has 2 divisors, whose sum is σ = 261695558. Its totient is φ = 261695556.

The previous prime is 261695537. The next prime is 261695611. The reversal of 261695557 is 755596162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 231070401 + 30625156 = 15201^2 + 5534^2 .

It is a cyclic number.

It is not a de Polignac number, because 261695557 - 2²⁷ = 127477829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261695527) 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, 130847778 + 130847779.

It is an arithmetic number, because the mean of its divisors is an integer number (130847779).

Almost surely, 2^261695557 is an apocalyptic number.

It is an amenable number.

261695557 is a deficient number, since it is larger than the sum of its proper divisors (1).

261695557 is an equidigital number, since it uses as much as digits as its factorization.

261695557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 567000, while the sum is 46.

The square root of 261695557 is about 16177.0070470406. The cubic root of 261695557 is about 639.6348478543.

The spelling of 261695557 in words is "two hundred sixty-one million, six hundred ninety-five thousand, five hundred fifty-seven".