261051221 has 4 divisors (see below), whose sum is σ = 262404012. Its totient is φ = 259698432.

The previous prime is 261051211. The next prime is 261051233. The reversal of 261051221 is 122150162.

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 98208100 + 162843121 = 9910^2 + 12761^2 .

It is a cyclic number.

It is not a de Polignac number, because 261051221 - 2¹⁰ = 261050197 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 261051193 and 261051202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261051211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 676106 + ... + 676491.

It is an arithmetic number, because the mean of its divisors is an integer number (65601003).

Almost surely, 2^261051221 is an apocalyptic number.

It is an amenable number.

261051221 is a deficient number, since it is larger than the sum of its proper divisors (1352791).

261051221 is a wasteful number, since it uses less digits than its factorization.

261051221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1352790.

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 261051221 is about 16157.0795937880. The cubic root of 261051221 is about 639.1094555770.

The spelling of 261051221 in words is "two hundred sixty-one million, fifty-one thousand, two hundred twenty-one".