261840686 has 4 divisors (see below), whose sum is σ = 392761032. Its totient is φ = 130920342.

The previous prime is 261840679. The next prime is 261840697. The reversal of 261840686 is 686048162.

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

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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, 65460170 + ... + 65460173.

It is an arithmetic number, because the mean of its divisors is an integer number (98190258).

Almost surely, 2^261840686 is an apocalyptic number.

261840686 is a deficient number, since it is larger than the sum of its proper divisors (130920346).

261840686 is a wasteful number, since it uses less digits than its factorization.

261840686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130920345.

The product of its (nonzero) digits is 110592, while the sum is 41.

The square root of 261840686 is about 16181.4920820053. The cubic root of 261840686 is about 639.7530671724.

The spelling of 261840686 in words is "two hundred sixty-one million, eight hundred forty thousand, six hundred eighty-six".