21002120110020 has 48 divisors (see below), whose sum is σ = 67206784353408. Its totient is φ = 4800484596480.

The previous prime is 21002120110007. The next prime is 21002120110067. The reversal of 21002120110020 is 2001102120012.

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 = 21002120109978 and 21002120110005.

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, 25002523521 + ... + 25002524360.

It is an arithmetic number, because the mean of its divisors is an integer number (1400141340696).

Almost surely, 2^{21002120110020} is an apocalyptic number.

21002120110020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21002120110020 is an abundant number, since it is smaller than the sum of its proper divisors (46204664243388).

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

21002120110020 is a wasteful number, since it uses less digits than its factorization.

21002120110020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50005047900 (or 50005047898 counting only the distinct ones).

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

Adding to 21002120110020 its reverse (2001102120012), we get a palindrome (23003222230032).

The spelling of 21002120110020 in words is "twenty-one trillion, two billion, one hundred twenty million, one hundred ten thousand, twenty".