261123221 has 4 divisors (see below), whose sum is σ = 270127500. Its totient is φ = 252118944.

The previous prime is 261123197. The next prime is 261123227. The reversal of 261123221 is 122321162.

261123221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 122321162 = 2 ⋅61160581.

It can be written as a sum of positive squares in 2 ways, for example, as 151167025 + 109956196 = 12295^2 + 10486^2 .

It is a cyclic number.

It is not a de Polignac number, because 261123221 - 2²⁶ = 194014357 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261123193 and 261123202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261123227) 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, 4502096 + ... + 4502153.

It is an arithmetic number, because the mean of its divisors is an integer number (67531875).

Almost surely, 2^261123221 is an apocalyptic number.

It is an amenable number.

261123221 is a deficient number, since it is larger than the sum of its proper divisors (9004279).

261123221 is an equidigital number, since it uses as much as digits as its factorization.

261123221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9004278.

The product of its digits is 288, while the sum is 20.

The square root of 261123221 is about 16159.3075656106. The cubic root of 261123221 is about 639.1682073305.

Adding to 261123221 its reverse (122321162), we get a palindrome (383444383).

The spelling of 261123221 in words is "two hundred sixty-one million, one hundred twenty-three thousand, two hundred twenty-one".