21213222100 has 54 divisors (see below), whose sum is σ = 53548245870. Its totient is φ = 7273103040.

The previous prime is 21213222089. The next prime is 21213222109. The reversal of 21213222100 is 122231212.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 797384644 + 20415837456 = 28238^2 + 142884^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213222109) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 2159715 + ... + 2169514.

Almost surely, 2^21213222100 is an apocalyptic number.

21213222100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21213222100 is an abundant number, since it is smaller than the sum of its proper divisors (32335023770).

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

21213222100 is a wasteful number, since it uses less digits than its factorization.

21213222100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4329257 (or 4329243 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21213222100 its reverse (122231212), we get a palindrome (21335453312).

The spelling of 21213222100 in words is "twenty-one billion, two hundred thirteen million, two hundred twenty-two thousand, one hundred".