20020020021 has 20 divisors (see below), whose sum is σ = 30124761612. Its totient is φ = 13249251648.

The previous prime is 20020020017. The next prime is 20020020043. The reversal of 20020020021 is 12002002002.

It can be written as a sum of positive squares in 2 ways, for example, as 4697046225 + 15322973796 = 68535^2 + 123786^2 .

It is not a de Polignac number, because 20020020021 - 2² = 20020020017 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 20020019985 and 20020020012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20020020091) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 890950 + ... + 913143.

Almost surely, 2^20020020021 is an apocalyptic number.

It is an amenable number.

20020020021 is a deficient number, since it is larger than the sum of its proper divisors (10104741591).

20020020021 is a wasteful number, since it uses less digits than its factorization.

20020020021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1804242 (or 1804233 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

Adding to 20020020021 its reverse (12002002002), we get a palindrome (32022022023).

The spelling of 20020020021 in words is "twenty billion, twenty million, twenty thousand, twenty-one".