20021220217 has 2 divisors, whose sum is σ = 20021220218. Its totient is φ = 20021220216.

The previous prime is 20021220199. The next prime is 20021220377. The reversal of 20021220217 is 71202212002.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14051494521 + 5969725696 = 118539^2 + 77264^2 .

It is a cyclic number.

It is not a de Polignac number, because 20021220217 - 2¹⁵ = 20021187449 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20021220194 and 20021220203.

It is not a weakly prime, because it can be changed into another prime (20021220617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10010610108 + 10010610109.

It is an arithmetic number, because the mean of its divisors is an integer number (10010610109).

Almost surely, 2^20021220217 is an apocalyptic number.

It is an amenable number.

20021220217 is a deficient number, since it is larger than the sum of its proper divisors (1).

20021220217 is an equidigital number, since it uses as much as digits as its factorization.

20021220217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 224, while the sum is 19.

Adding to 20021220217 its reverse (71202212002), we get a palindrome (91223432219).

The spelling of 20021220217 in words is "twenty billion, twenty-one million, two hundred twenty thousand, two hundred seventeen".