21022001100 has 216 divisors, whose sum is σ = 70425836208. Its totient is φ = 5226393600.

The previous prime is 21022001089. The next prime is 21022001101. The reversal of 21022001100 is 110022012.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (21022001101) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1630680 + ... + 1643520.

It is an arithmetic number, because the mean of its divisors is an integer number (326045538).

Almost surely, 2^21022001100 is an apocalyptic number.

21022001100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21022001100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35212918104).

21022001100 is an abundant number, since it is smaller than the sum of its proper divisors (49403835108).

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

21022001100 is a wasteful number, since it uses less digits than its factorization.

21022001100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12985 (or 12975 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21022001100 its reverse (110022012), we get a palindrome (21132023112).

The spelling of 21022001100 in words is "twenty-one billion, twenty-two million, one thousand, one hundred".