21021212020 has 192 divisors, whose sum is σ = 50534668800. Its totient is φ = 7302113280.

The previous prime is 21021211987. The next prime is 21021212041. The reversal of 21021212020 is 2021212012.

It is a happy number.

It is a congruent number.

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, 49931410 + ... + 49931830.

It is an arithmetic number, because the mean of its divisors is an integer number (263201400).

Almost surely, 2^21021212020 is an apocalyptic number.

21021212020 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 21021212020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25267334400).

21021212020 is an abundant number, since it is smaller than the sum of its proper divisors (29513456780).

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

21021212020 is a wasteful number, since it uses less digits than its factorization.

21021212020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 698 (or 696 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 21021212020 its reverse (2021212012), we get a palindrome (23042424032).

The spelling of 21021212020 in words is "twenty-one billion, twenty-one million, two hundred twelve thousand, twenty".