21121000120020 has 48 divisors (see below), whose sum is σ = 59139396146880. Its totient is φ = 5632209954816.

The previous prime is 21121000120009. The next prime is 21121000120091. The reversal of 21121000120020 is 2002100012112.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21121000119978 and 21121000120005.

It is a congruent number.

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, 4410036 + ... + 7854324.

It is an arithmetic number, because the mean of its divisors is an integer number (1232070753060).

Almost surely, 2^{21121000120020} is an apocalyptic number.

21121000120020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21121000120020 is an abundant number, since it is smaller than the sum of its proper divisors (38018396026860).

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

21121000120020 is a wasteful number, since it uses less digits than its factorization.

21121000120020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3546504 (or 3546502 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21121000120020 its reverse (2002100012112), we get a palindrome (23123100132132).

The spelling of 21121000120020 in words is "twenty-one trillion, one hundred twenty-one billion, one hundred twenty thousand, twenty".