261221017 has 4 divisors (see below), whose sum is σ = 261274896. Its totient is φ = 261167140.

The previous prime is 261220991. The next prime is 261221021. The reversal of 261221017 is 710122162.

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, and also an emirpimes, since its reverse is a distinct semiprime: 710122162 = 2 ⋅355061081.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261221017 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261221027) 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, 18859 + ... + 29632.

It is an arithmetic number, because the mean of its divisors is an integer number (65318724).

Almost surely, 2^261221017 is an apocalyptic number.

It is an amenable number.

261221017 is a deficient number, since it is larger than the sum of its proper divisors (53879).

261221017 is an equidigital number, since it uses as much as digits as its factorization.

261221017 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53878.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 261221017 is about 16162.3332783358. Note that the first 3 decimals coincide. The cubic root of 261221017 is about 639.2479912372.

Adding to 261221017 its reverse (710122162), we get a palindrome (971343179).

The spelling of 261221017 in words is "two hundred sixty-one million, two hundred twenty-one thousand, seventeen".