261686497 has 4 divisors (see below), whose sum is σ = 261805716. Its totient is φ = 261567280.

The previous prime is 261686489. The next prime is 261686507. The reversal of 261686497 is 794686162.

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

It can be written as a sum of positive squares in 2 ways, for example, as 97436641 + 164249856 = 9871^2 + 12816^2 .

It is a cyclic number.

It is not a de Polignac number, because 261686497 - 2³ = 261686489 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261686497.

It is not an unprimeable number, because it can be changed into a prime (261686897) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 56254 + ... + 60727.

It is an arithmetic number, because the mean of its divisors is an integer number (65451429).

Almost surely, 2^261686497 is an apocalyptic number.

It is an amenable number.

261686497 is a deficient number, since it is larger than the sum of its proper divisors (119219).

261686497 is a wasteful number, since it uses less digits than its factorization.

261686497 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 119218.

The product of its digits is 870912, while the sum is 49.

The square root of 261686497 is about 16176.7270175397. The cubic root of 261686497 is about 639.6274663017.

The spelling of 261686497 in words is "two hundred sixty-one million, six hundred eighty-six thousand, four hundred ninety-seven".