261841813 has 2 divisors, whose sum is σ = 261841814. Its totient is φ = 261841812.

The previous prime is 261841807. The next prime is 261841861. The reversal of 261841813 is 318148162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 163891204 + 97950609 = 12802^2 + 9897^2 .

It is a cyclic number.

It is not a de Polignac number, because 261841813 - 2⁹ = 261841301 is a prime.

It is a super-2 number, since 2×261841813² = 137122270070253938, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261841873) 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, 130920906 + 130920907.

It is an arithmetic number, because the mean of its divisors is an integer number (130920907).

Almost surely, 2^261841813 is an apocalyptic number.

It is an amenable number.

261841813 is a deficient number, since it is larger than the sum of its proper divisors (1).

261841813 is an equidigital number, since it uses as much as digits as its factorization.

261841813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9216, while the sum is 34.

The square root of 261841813 is about 16181.5269057033. The cubic root of 261841813 is about 639.7539850342.

Adding to 261841813 its reverse (318148162), we get a palindrome (579989975).

The spelling of 261841813 in words is "two hundred sixty-one million, eight hundred forty-one thousand, eight hundred thirteen".