20021321 has 2 divisors, whose sum is σ = 20021322. Its totient is φ = 20021320.

The previous prime is 20021311. The next prime is 20021327. The reversal of 20021321 is 12312002.

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., 17131321 + 2890000 = 4139^2 + 1700^2 .

It is a cyclic number.

It is not a de Polignac number, because 20021321 - 2¹⁸ = 19759177 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20021327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10010660 + 10010661.

It is an arithmetic number, because the mean of its divisors is an integer number (10010661).

Almost surely, 2^20021321 is an apocalyptic number.

It is an amenable number.

20021321 is a deficient number, since it is larger than the sum of its proper divisors (1).

20021321 is an equidigital number, since it uses as much as digits as its factorization.

20021321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 20021321 is about 4474.5190803035. The cubic root of 20021321 is about 271.5381842338.

Adding to 20021321 its reverse (12312002), we get a palindrome (32333323).

The spelling of 20021321 in words is "twenty million, twenty-one thousand, three hundred twenty-one".