21221002012 has 96 divisors (see below), whose sum is σ = 46603468800. Its totient is φ = 8245186560.

The previous prime is 21221002001. The next prime is 21221002027. The reversal of 21221002012 is 21020012212.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21221001983 and 21221002001.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3287364 + ... + 3293812.

It is an arithmetic number, because the mean of its divisors is an integer number (485452800).

Almost surely, 2^21221002012 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 21221002012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23301734400).

21221002012 is an abundant number, since it is smaller than the sum of its proper divisors (25382466788).

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

21221002012 is a wasteful number, since it uses less digits than its factorization.

21221002012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6731 (or 6729 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 21221002012 its reverse (21020012212), we get a palindrome (42241014224).

The spelling of 21221002012 in words is "twenty-one billion, two hundred twenty-one million, two thousand, twelve".