1221705217 has 8 divisors (see below), whose sum is σ = 1238128640. Its totient is φ = 1205305920.

The previous prime is 1221705181. The next prime is 1221705229. The reversal of 1221705217 is 7125071221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221705217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221705917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 110953 + ... + 121465.

It is an arithmetic number, because the mean of its divisors is an integer number (154766080).

Almost surely, 2^1221705217 is an apocalyptic number.

It is an amenable number.

1221705217 is a deficient number, since it is larger than the sum of its proper divisors (16423423).

1221705217 is a wasteful number, since it uses less digits than its factorization.

1221705217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12063.

The product of its (nonzero) digits is 1960, while the sum is 28.

The square root of 1221705217 is about 34952.8999798300. The cubic root of 1221705217 is about 1069.0273331006.

Adding to 1221705217 its reverse (7125071221), we get a palindrome (8346776438).

The spelling of 1221705217 in words is "one billion, two hundred twenty-one million, seven hundred five thousand, two hundred seventeen".