20001212221 has 2 divisors, whose sum is σ = 20001212222. Its totient is φ = 20001212220.

The previous prime is 20001212191. The next prime is 20001212233. The reversal of 20001212221 is 12221210002.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10735032100 + 9266180121 = 103610^2 + 96261^2 .

It is a cyclic number.

It is not a de Polignac number, because 20001212221 - 2²⁷ = 19866994493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20001212251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10000606110 + 10000606111.

It is an arithmetic number, because the mean of its divisors is an integer number (10000606111).

Almost surely, 2^20001212221 is an apocalyptic number.

It is an amenable number.

20001212221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20001212221 is an equidigital number, since it uses as much as digits as its factorization.

20001212221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 20001212221 its reverse (12221210002), we get a palindrome (32222422223).

The spelling of 20001212221 in words is "twenty billion, one million, two hundred twelve thousand, two hundred twenty-one".