20210001221 has 2 divisors, whose sum is σ = 20210001222. Its totient is φ = 20210001220.

The previous prime is 20210001179. The next prime is 20210001223. The reversal of 20210001221 is 12210001202.

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., 18600868225 + 1609132996 = 136385^2 + 40114^2 .

It is a cyclic number.

It is not a de Polignac number, because 20210001221 - 2²² = 20205806917 is a prime.

It is a Sophie Germain prime.

Together with 20210001223, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20210001223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10105000610 + 10105000611.

It is an arithmetic number, because the mean of its divisors is an integer number (10105000611).

Almost surely, 2^20210001221 is an apocalyptic number.

It is an amenable number.

20210001221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20210001221 is an equidigital number, since it uses as much as digits as its factorization.

20210001221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 20210001221 its reverse (12210001202), we get a palindrome (32420002423).

The spelling of 20210001221 in words is "twenty billion, two hundred ten million, one thousand, two hundred twenty-one".