20000021221 has 2 divisors, whose sum is σ = 20000021222. Its totient is φ = 20000021220.

The previous prime is 20000021203. The next prime is 20000021231. The reversal of 20000021221 is 12212000002.

It is an a-pointer prime, because the next prime (20000021231) can be obtained adding 20000021221 to its sum of digits (10).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10996668225 + 9003352996 = 104865^2 + 94886^2 .

It is a cyclic number.

It is not a de Polignac number, because 20000021221 - 2⁹ = 20000020709 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20000021198 and 20000021207.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20000021201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10000010610 + 10000010611.

It is an arithmetic number, because the mean of its divisors is an integer number (10000010611).

Almost surely, 2^20000021221 is an apocalyptic number.

It is an amenable number.

20000021221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20000021221 is an equidigital number, since it uses as much as digits as its factorization.

20000021221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 10.

Adding to 20000021221 its reverse (12212000002), we get a palindrome (32212021223).

It can be divided in two parts, 2000002 and 1221, that multiplied together give a palindrome (2442002442).

The spelling of 20000021221 in words is "twenty billion, twenty-one thousand, two hundred twenty-one".