20021020421 has 4 divisors (see below), whose sum is σ = 20021599500. Its totient is φ = 20020441344.

The previous prime is 20021020361. The next prime is 20021020429. The reversal of 20021020421 is 12402012002.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13061289796 + 6959730625 = 114286^2 + 83425^2 .

It is a cyclic number.

It is not a de Polignac number, because 20021020421 - 2²⁶ = 19953911557 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20021020396 and 20021020405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20021020429) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 234146 + ... + 308003.

It is an arithmetic number, because the mean of its divisors is an integer number (5005399875).

Almost surely, 2^20021020421 is an apocalyptic number.

It is an amenable number.

20021020421 is a deficient number, since it is larger than the sum of its proper divisors (579079).

20021020421 is an equidigital number, since it uses as much as digits as its factorization.

20021020421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 579078.

The product of its (nonzero) digits is 64, while the sum is 14.

Adding to 20021020421 its reverse (12402012002), we get a palindrome (32423032423).

The spelling of 20021020421 in words is "twenty billion, twenty-one million, twenty thousand, four hundred twenty-one".