261256655671 has 4 divisors (see below), whose sum is σ = 285007260744. Its totient is φ = 237506050600.

The previous prime is 261256655669. The next prime is 261256655677. The reversal of 261256655671 is 176556652162.

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 261256655671 - 2¹ = 261256655669 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 (261256655677) 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, 11875302520 + ... + 11875302541.

It is an arithmetic number, because the mean of its divisors is an integer number (71251815186).

Almost surely, 2^261256655671 is an apocalyptic number.

261256655671 is a deficient number, since it is larger than the sum of its proper divisors (23750605073).

261256655671 is a wasteful number, since it uses less digits than its factorization.

261256655671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23750605072.

The product of its digits is 4536000, while the sum is 52.

The spelling of 261256655671 in words is "two hundred sixty-one billion, two hundred fifty-six million, six hundred fifty-five thousand, six hundred seventy-one".