21202021100 has 72 divisors (see below), whose sum is σ = 49636302240. Its totient is φ = 7814407680.

The previous prime is 21202021097. The next prime is 21202021103. The reversal of 21202021100 is 112020212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21202021097) and next prime (21202021103).

It is not an unprimeable number, because it can be changed into a prime (21202021103) 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, 725369 + ... + 754031.

Almost surely, 2^21202021100 is an apocalyptic number.

21202021100 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 21202021100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24818151120).

21202021100 is an abundant number, since it is smaller than the sum of its proper divisors (28434281140).

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

21202021100 is a wasteful number, since it uses less digits than its factorization.

21202021100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29259 (or 29252 counting only the distinct ones).

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

Adding to 21202021100 its reverse (112020212), we get a palindrome (21314041312).

The spelling of 21202021100 in words is "twenty-one billion, two hundred two million, twenty-one thousand, one hundred".