21212120120020 has 12 divisors (see below), whose sum is σ = 44545452252084. Its totient is φ = 8484848048000.

The previous prime is 21212120120011. The next prime is 21212120120021. The reversal of 21212120120020 is 2002102121212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 2212947809604 + 18999172310416 = 1487598^2 + 4358804^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21212120119976 and 21212120120003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212120120021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 530303002981 + ... + 530303003020.

It is an arithmetic number, because the mean of its divisors is an integer number (3712121021007).

Almost surely, 2^{21212120120020} is an apocalyptic number.

21212120120020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21212120120020 is an abundant number, since it is smaller than the sum of its proper divisors (23333332132064).

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

21212120120020 is a wasteful number, since it uses less digits than its factorization.

21212120120020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1060606006010 (or 1060606006008 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21212120120020 its reverse (2002102121212), we get a palindrome (23214222241232).

The spelling of 21212120120020 in words is "twenty-one trillion, two hundred twelve billion, one hundred twenty million, one hundred twenty thousand, twenty".