20201021221 has 2 divisors, whose sum is σ = 20201021222. Its totient is φ = 20201021220.

The previous prime is 20201021201. The next prime is 20201021227. The reversal of 20201021221 is 12212010202.

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., 16157968996 + 4043052225 = 127114^2 + 63585^2 .

It is a cyclic number.

It is not a de Polignac number, because 20201021221 - 2¹¹ = 20201019173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20201021227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10100510610 + 10100510611.

It is an arithmetic number, because the mean of its divisors is an integer number (10100510611).

Almost surely, 2^20201021221 is an apocalyptic number.

It is an amenable number.

20201021221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20201021221 is an equidigital number, since it uses as much as digits as its factorization.

20201021221 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 20201021221 its reverse (12212010202), we get a palindrome (32413031423).

The spelling of 20201021221 in words is "twenty billion, two hundred one million, twenty-one thousand, two hundred twenty-one".