261318311 has 4 divisors (see below), whose sum is σ = 261885624. Its totient is φ = 260751000.

The previous prime is 261318307. The next prime is 261318331. The reversal of 261318311 is 113813162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 261318311 - 2² = 261318307 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261318331) 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 in 3 ways as a sum of consecutive naturals, for example, 282965 + ... + 283886.

It is an arithmetic number, because the mean of its divisors is an integer number (65471406).

Almost surely, 2^261318311 is an apocalyptic number.

261318311 is a deficient number, since it is larger than the sum of its proper divisors (567313).

261318311 is an equidigital number, since it uses as much as digits as its factorization.

261318311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 567312.

The product of its digits is 864, while the sum is 26.

The square root of 261318311 is about 16165.3428976932. The cubic root of 261318311 is about 639.3273458449.

The spelling of 261318311 in words is "two hundred sixty-one million, three hundred eighteen thousand, three hundred eleven".