21022120100 has 54 divisors (see below), whose sum is σ = 48459326790. Its totient is φ = 7914199040.

The previous prime is 21022120043. The next prime is 21022120121. The reversal of 21022120100 is 102122012.

It is a happy number.

It can be written as a sum of positive squares in 9 ways, for example, as 27269284 + 20994850816 = 5222^2 + 144896^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 334805 + ... + 392604.

Almost surely, 2^21022120100 is an apocalyptic number.

21022120100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21022120100 is an abundant number, since it is smaller than the sum of its proper divisors (27437206690).

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

21022120100 is a wasteful number, since it uses less digits than its factorization.

21022120100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 727457 (or 727433 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21022120100 its reverse (102122012), we get a palindrome (21124242112).

The spelling of 21022120100 in words is "twenty-one billion, twenty-two million, one hundred twenty thousand, one hundred".