21021022020 has 192 divisors, whose sum is σ = 62730904320. Its totient is φ = 5244715008.

The previous prime is 21021021979. The next prime is 21021022049. The reversal of 21021022020 is 2022012012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21021021987 and 21021022005.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 45997632 + ... + 45998088.

It is an arithmetic number, because the mean of its divisors is an integer number (326723460).

Almost surely, 2^21021022020 is an apocalyptic number.

21021022020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21021022020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31365452160).

21021022020 is an abundant number, since it is smaller than the sum of its proper divisors (41709882300).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21021022020 is a wasteful number, since it uses less digits than its factorization.

21021022020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 902 (or 900 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 12.

Adding to 21021022020 its reverse (2022012012), we get a palindrome (23043034032).

The spelling of 21021022020 in words is "twenty-one billion, twenty-one million, twenty-two thousand, twenty".