261512221 has 4 divisors (see below), whose sum is σ = 261615744. Its totient is φ = 261408700.

The previous prime is 261512201. The next prime is 261512243. The reversal of 261512221 is 122215162.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 122215162 = 2 ⋅61107581.

It is a cyclic number.

It is not a de Polignac number, because 261512221 - 2¹³ = 261504029 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261512192 and 261512201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261512201) 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, 47875 + ... + 53056.

It is an arithmetic number, because the mean of its divisors is an integer number (65403936).

Almost surely, 2^261512221 is an apocalyptic number.

It is an amenable number.

261512221 is a deficient number, since it is larger than the sum of its proper divisors (103523).

261512221 is a wasteful number, since it uses less digits than its factorization.

261512221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103522.

The product of its digits is 480, while the sum is 22.

The square root of 261512221 is about 16171.3394930661. The cubic root of 261512221 is about 639.4854433436.

Adding to 261512221 its reverse (122215162), we get a palindrome (383727383).

The spelling of 261512221 in words is "two hundred sixty-one million, five hundred twelve thousand, two hundred twenty-one".