261220 has 24 divisors (see below), whose sum is σ = 564984. Its totient is φ = 101376.

The previous prime is 261169. The next prime is 261223. The reversal of 261220 is 22162.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 60516 + 200704 = 246^2 + 448^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 261220.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 564 + ... + 916.

It is an arithmetic number, because the mean of its divisors is an integer number (23541).

2²⁶¹²²⁰ is an apocalyptic number.

261220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (282492).

261220 is an abundant number, since it is smaller than the sum of its proper divisors (303764).

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

261220 is a wasteful number, since it uses less digits than its factorization.

261220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399 (or 397 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 261220 is about 511.0968597047. The cubic root of 261220 is about 63.9247161651.

Adding to 261220 its reverse (22162), we get a palindrome (283382).

The spelling of 261220 in words is "two hundred sixty-one thousand, two hundred twenty".