261686505 has 8 divisors (see below), whose sum is σ = 418698432. Its totient is φ = 139566128.

The previous prime is 261686489. The next prime is 261686507. The reversal of 261686505 is 505686162.

261686505 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 261686505 - 2⁴ = 261686489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261686507) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8722869 + ... + 8722898.

It is an arithmetic number, because the mean of its divisors is an integer number (52337304).

Almost surely, 2^261686505 is an apocalyptic number.

It is an amenable number.

261686505 is a deficient number, since it is larger than the sum of its proper divisors (157011927).

261686505 is a wasteful number, since it uses less digits than its factorization.

261686505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17445775.

The product of its (nonzero) digits is 86400, while the sum is 39.

The square root of 261686505 is about 16176.7272648085. The cubic root of 261686505 is about 639.6274728197.

The spelling of 261686505 in words is "two hundred sixty-one million, six hundred eighty-six thousand, five hundred five".