21212210020 has 48 divisors (see below), whose sum is σ = 47217446640. Its totient is φ = 7977058304.

The previous prime is 21212209951. The next prime is 21212210059. The reversal of 21212210020 is 2001221212.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 5772656484 + 15439553536 = 75978^2 + 124256^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 282282 + ... + 349438.

It is an arithmetic number, because the mean of its divisors is an integer number (983696805).

Almost surely, 2^21212210020 is an apocalyptic number.

21212210020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21212210020 is an abundant number, since it is smaller than the sum of its proper divisors (26005236620).

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

21212210020 is a wasteful number, since it uses less digits than its factorization.

21212210020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68112 (or 68110 counting only the distinct ones).

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

Adding to 21212210020 its reverse (2001221212), we get a palindrome (23213431232).

The spelling of 21212210020 in words is "twenty-one billion, two hundred twelve million, two hundred ten thousand, twenty".