261660671 has 4 divisors (see below), whose sum is σ = 261863712. Its totient is φ = 261457632.

The previous prime is 261660643. The next prime is 261660683. The reversal of 261660671 is 176066162.

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 261660671 - 2¹⁰ = 261659647 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 (261660611) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99575 + ... + 102168.

It is an arithmetic number, because the mean of its divisors is an integer number (65465928).

Almost surely, 2^261660671 is an apocalyptic number.

261660671 is a deficient number, since it is larger than the sum of its proper divisors (203041).

261660671 is a wasteful number, since it uses less digits than its factorization.

261660671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 203040.

The product of its (nonzero) digits is 18144, while the sum is 35.

The square root of 261660671 is about 16175.9287523159. The cubic root of 261660671 is about 639.6064238678.

The spelling of 261660671 in words is "two hundred sixty-one million, six hundred sixty thousand, six hundred seventy-one".