21000120012020 has 24 divisors (see below), whose sum is σ = 45620950372200. Its totient is φ = 8110391176832.

The previous prime is 21000120012019. The next prime is 21000120012037. The reversal of 21000120012020 is 2021002100012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 2258389806436 + 18741730205584 = 1502794^2 + 4329172^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21000120011992 and 21000120012010.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18103551155 + ... + 18103552314.

It is an arithmetic number, because the mean of its divisors is an integer number (1900872932175).

Almost surely, 2^{21000120012020} is an apocalyptic number.

21000120012020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21000120012020 is an abundant number, since it is smaller than the sum of its proper divisors (24620830360180).

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

21000120012020 is a wasteful number, since it uses less digits than its factorization.

21000120012020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36207103507 (or 36207103505 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21000120012020 its reverse (2021002100012), we get a palindrome (23021122112032).

The spelling of 21000120012020 in words is "twenty-one trillion, one hundred twenty million, twelve thousand, twenty".