21021311444 has 72 divisors (see below), whose sum is σ = 46364693760. Its totient is φ = 8281937664.

The previous prime is 21021311417. The next prime is 21021311459. The reversal of 21021311444 is 44411312012.

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 23 ways as a sum of consecutive naturals, for example, 69917 + ... + 216635.

It is an arithmetic number, because the mean of its divisors is an integer number (643954080).

Almost surely, 2^21021311444 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 21021311444, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23182346880).

21021311444 is an abundant number, since it is smaller than the sum of its proper divisors (25343382316).

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

21021311444 is a wasteful number, since it uses less digits than its factorization.

21021311444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146797 (or 146788 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 23.

Adding to 21021311444 its reverse (44411312012), we get a palindrome (65432623456).

The spelling of 21021311444 in words is "twenty-one billion, twenty-one million, three hundred eleven thousand, four hundred forty-four".