261317221 has 4 divisors (see below), whose sum is σ = 285073344. Its totient is φ = 237561100.

The previous prime is 261317207. The next prime is 261317239. The reversal of 261317221 is 122713162.

It is a happy number.

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.

It is a cyclic number.

It is not a de Polignac number, because 261317221 - 2¹³ = 261309029 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261317201) 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, 11878045 + ... + 11878066.

It is an arithmetic number, because the mean of its divisors is an integer number (71268336).

Almost surely, 2^261317221 is an apocalyptic number.

It is an amenable number.

261317221 is a deficient number, since it is larger than the sum of its proper divisors (23756123).

261317221 is a wasteful number, since it uses less digits than its factorization.

261317221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23756122.

The product of its digits is 1008, while the sum is 25.

The square root of 261317221 is about 16165.3091835572. The cubic root of 261317221 is about 639.3264569318.

The spelling of 261317221 in words is "two hundred sixty-one million, three hundred seventeen thousand, two hundred twenty-one".