261216 has 36 divisors (see below), whose sum is σ = 743652. Its totient is φ = 86976.

The previous prime is 261169. The next prime is 261223. The reversal of 261216 is 612162.

It is a happy number.

261216 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is a nialpdrome in base 6.

It is a zygodrome in base 2.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 166 + ... + 741.

It is an arithmetic number, because the mean of its divisors is an integer number (20657).

2²⁶¹²¹⁶ is an apocalyptic number.

It is an amenable number.

261216 is an abundant number, since it is smaller than the sum of its proper divisors (482436).

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

261216 is a wasteful number, since it uses less digits than its factorization.

261216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 923 (or 912 counting only the distinct ones).

The product of its digits is 144, while the sum is 18.

The square root of 261216 is about 511.0929465371. The cubic root of 261216 is about 63.9243898754.

Adding to 261216 its reverse (612162), we get a palindrome (873378).

It can be divided in two parts, 2612 and 16, that added together give a triangular number (2628 = T₇₂).

The spelling of 261216 in words is "two hundred sixty-one thousand, two hundred sixteen".