261317215 has 4 divisors (see below), whose sum is σ = 313580664. Its totient is φ = 209053768.

The previous prime is 261317207. The next prime is 261317239. The reversal of 261317215 is 512713162.

It is a happy number.

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 261317215 - 2³ = 261317207 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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, 26131717 + ... + 26131726.

It is an arithmetic number, because the mean of its divisors is an integer number (78395166).

Almost surely, 2^261317215 is an apocalyptic number.

261317215 is a deficient number, since it is larger than the sum of its proper divisors (52263449).

261317215 is an equidigital number, since it uses as much as digits as its factorization.

261317215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52263448.

The product of its digits is 2520, while the sum is 28.

The square root of 261317215 is about 16165.3089979746. The cubic root of 261317215 is about 639.3264520387.

The spelling of 261317215 in words is "two hundred sixty-one million, three hundred seventeen thousand, two hundred fifteen".