261618 has 16 divisors (see below), whose sum is σ = 598080. Its totient is φ = 74736.

The previous prime is 261601. The next prime is 261619. The reversal of 261618 is 816162.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261619) 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, 3073 + ... + 3156.

It is an arithmetic number, because the mean of its divisors is an integer number (37380).

2²⁶¹⁶¹⁸ is an apocalyptic number.

261618 is an abundant number, since it is smaller than the sum of its proper divisors (336462).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261618 is a wasteful number, since it uses less digits than its factorization.

261618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6241.

The product of its digits is 576, while the sum is 24.

The square root of 261618 is about 511.4860701916. The cubic root of 261618 is about 63.9571653479.

The spelling of 261618 in words is "two hundred sixty-one thousand, six hundred eighteen".