20500447021 has 2 divisors, whose sum is σ = 20500447022. Its totient is φ = 20500447020.

The previous prime is 20500447013. The next prime is 20500447039. The reversal of 20500447021 is 12074400502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20082857796 + 417589225 = 141714^2 + 20435^2 .

It is a cyclic number.

It is not a de Polignac number, because 20500447021 - 2³ = 20500447013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20500447091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10250223510 + 10250223511.

It is an arithmetic number, because the mean of its divisors is an integer number (10250223511).

Almost surely, 2^20500447021 is an apocalyptic number.

It is an amenable number.

20500447021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20500447021 is an equidigital number, since it uses as much as digits as its factorization.

20500447021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2240, while the sum is 25.

Adding to 20500447021 its reverse (12074400502), we get a palindrome (32574847523).

The spelling of 20500447021 in words is "twenty billion, five hundred million, four hundred forty-seven thousand, twenty-one".