21001231020020 has 24 divisors (see below), whose sum is σ = 44102763268200. Its totient is φ = 8400458479232.

The previous prime is 21001231020001. The next prime is 21001231020169. The reversal of 21001231020020 is 2002013210012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 2296540208356 + 18704690811664 = 1515434^2 + 4324892^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21001231019977 and 21001231020004.

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, 3292046 + ... + 7269114.

It is an arithmetic number, because the mean of its divisors is an integer number (1837615136175).

Almost surely, 2^{21001231020020} is an apocalyptic number.

21001231020020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001231020020 is an abundant number, since it is smaller than the sum of its proper divisors (23101532248180).

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

21001231020020 is a wasteful number, since it uses less digits than its factorization.

21001231020020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4241107 (or 4241105 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 14.

Adding to 21001231020020 its reverse (2002013210012), we get a palindrome (23003244230032).

The spelling of 21001231020020 in words is "twenty-one trillion, one billion, two hundred thirty-one million, twenty thousand, twenty".