21210122120020 has 48 divisors (see below), whose sum is σ = 46159886359440. Its totient is φ = 8176788859904.

The previous prime is 21210122119993. The next prime is 21210122120023. The reversal of 21210122120020 is 2002122101212.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 5620227972804 + 15589894147216 = 2370702^2 + 3948404^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21210122119976 and 21210122120003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210122120023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32503849 + ... + 33149968.

It is an arithmetic number, because the mean of its divisors is an integer number (961664299155).

Almost surely, 2^{21210122120020} is an apocalyptic number.

21210122120020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21210122120020 is an abundant number, since it is smaller than the sum of its proper divisors (24949764239420).

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

21210122120020 is a wasteful number, since it uses less digits than its factorization.

21210122120020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65654412 (or 65654410 counting only the distinct ones).

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

Adding to 21210122120020 its reverse (2002122101212), we get a palindrome (23212244221232).

The spelling of 21210122120020 in words is "twenty-one trillion, two hundred ten billion, one hundred twenty-two million, one hundred twenty thousand, twenty".