21021220212100 has 36 divisors (see below), whose sum is σ = 46728634402548. Its totient is φ = 8203403008000.

The previous prime is 21021220212077. The next prime is 21021220212119. The reversal of 21021220212100 is 121202212012.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 3438495245124 + 17582724966976 = 1854318^2 + 4193176^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2563559341 + ... + 2563567540.

It is an arithmetic number, because the mean of its divisors is an integer number (1298017622293).

Almost surely, 2^{21021220212100} is an apocalyptic number.

21021220212100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021220212100 is an abundant number, since it is smaller than the sum of its proper divisors (25707414190448).

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

21021220212100 is a wasteful number, since it uses less digits than its factorization.

21021220212100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5127126936 (or 5127126929 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21021220212100 its reverse (121202212012), we get a palindrome (21142422424112).

The spelling of 21021220212100 in words is "twenty-one trillion, twenty-one billion, two hundred twenty million, two hundred twelve thousand, one hundred".