261813611 has 2 divisors, whose sum is σ = 261813612. Its totient is φ = 261813610.

The previous prime is 261813599. The next prime is 261813613. The reversal of 261813611 is 116318162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261813611 - 2¹⁴ = 261797227 is a prime.

Together with 261813613, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (261813613) 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, 130906805 + 130906806.

It is an arithmetic number, because the mean of its divisors is an integer number (130906806).

Almost surely, 2^261813611 is an apocalyptic number.

261813611 is a deficient number, since it is larger than the sum of its proper divisors (1).

261813611 is an equidigital number, since it uses as much as digits as its factorization.

261813611 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1728, while the sum is 29.

The square root of 261813611 is about 16180.6554564393. The cubic root of 261813611 is about 639.7310157085.

It can be divided in two parts, 26181 and 3611, that added together give a palindrome (29792).

The spelling of 261813611 in words is "two hundred sixty-one million, eight hundred thirteen thousand, six hundred eleven".