261221 has 4 divisors (see below), whose sum is σ = 264012. Its totient is φ = 258432.

The previous prime is 261169. The next prime is 261223. The reversal of 261221 is 122162.

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 112225 + 148996 = 335^2 + 386^2 .

It is a cyclic number.

It is not a de Polignac number, because 261221 - 2¹⁴ = 244837 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261196 and 261205.

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 polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1250 + ... + 1443.

It is an arithmetic number, because the mean of its divisors is an integer number (66003).

2²⁶¹²²¹ is an apocalyptic number.

It is an amenable number.

261221 is a deficient number, since it is larger than the sum of its proper divisors (2791).

261221 is an equidigital number, since it uses as much as digits as its factorization.

261221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2790.

The product of its digits is 48, while the sum is 14.

The square root of 261221 is about 511.0978379919. The cubic root of 261221 is about 63.9247977370.

Adding to 261221 its reverse (122162), we get a palindrome (383383).

The spelling of 261221 in words is "two hundred sixty-one thousand, two hundred twenty-one".