21000020221220 has 12 divisors (see below), whose sum is σ = 44100042464604. Its totient is φ = 8400008088480.

The previous prime is 21000020221163. The next prime is 21000020221223. The reversal of 21000020221220 is 2212202000012.

It can be written as a sum of positive squares in 2 ways, for example, as 16342469226724 + 4657550994496 = 4042582^2 + 2158136^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21000020221195 and 21000020221204.

It is not an unprimeable number, because it can be changed into a prime (21000020221223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 525000505511 + ... + 525000505550.

It is an arithmetic number, because the mean of its divisors is an integer number (3675003538717).

Almost surely, 2^{21000020221220} is an apocalyptic number.

21000020221220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21000020221220 is an abundant number, since it is smaller than the sum of its proper divisors (23100022243384).

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

21000020221220 is a wasteful number, since it uses less digits than its factorization.

21000020221220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1050001011070 (or 1050001011068 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 14.

Adding to 21000020221220 its reverse (2212202000012), we get a palindrome (23212222221232).

The spelling of 21000020221220 in words is "twenty-one trillion, twenty million, two hundred twenty-one thousand, two hundred twenty".