21213103212 has 144 divisors (see below), whose sum is σ = 63402393600. Its totient is φ = 5852096640.

The previous prime is 21213103189. The next prime is 21213103237. The reversal of 21213103212 is 21230131212.

21213103212 is a `hidden beast` number, since 212 + 131 + 0 + 321 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3739114 + ... + 3744782.

It is an arithmetic number, because the mean of its divisors is an integer number (440294400).

Almost surely, 2^21213103212 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21213103212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31701196800).

21213103212 is an abundant number, since it is smaller than the sum of its proper divisors (42189290388).

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

21213103212 is a wasteful number, since it uses less digits than its factorization.

21213103212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6196 (or 6191 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21213103212 its reverse (21230131212), we get a palindrome (42443234424).

The spelling of 21213103212 in words is "twenty-one billion, two hundred thirteen million, one hundred three thousand, two hundred twelve".