21201201100 has 72 divisors (see below), whose sum is σ = 47879123040. Its totient is φ = 8138833920.

The previous prime is 21201201083. The next prime is 21201201107. The reversal of 21201201100 is 110210212.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is not an unprimeable number, because it can be changed into a prime (21201201107) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 462412 + ... + 506188.

It is an arithmetic number, because the mean of its divisors is an integer number (664987820).

Almost surely, 2^21201201100 is an apocalyptic number.

21201201100 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 21201201100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23939561520).

21201201100 is an abundant number, since it is smaller than the sum of its proper divisors (26677921940).

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

21201201100 is a wasteful number, since it uses less digits than its factorization.

21201201100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43987 (or 43980 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21201201100 its reverse (110210212), we get a palindrome (21311411312).

The spelling of 21201201100 in words is "twenty-one billion, two hundred one million, two hundred one thousand, one hundred".