21001333312 has 56 divisors (see below), whose sum is σ = 42349769504. Its totient is φ = 10330924032.

The previous prime is 21001333307. The next prime is 21001333387. The reversal of 21001333312 is 21333310012.

It is a self number, because there is not a number n which added to its sum of digits gives 21001333312.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4015243 + ... + 4020469.

It is an arithmetic number, because the mean of its divisors is an integer number (756245884).

Almost surely, 2^21001333312 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 21001333312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21174884752).

21001333312 is an abundant number, since it is smaller than the sum of its proper divisors (21348436192).

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

21001333312 is an equidigital number, since it uses as much as digits as its factorization.

21001333312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6243 (or 6233 counting only the distinct ones).

The product of its (nonzero) digits is 324, while the sum is 19.

Adding to 21001333312 its reverse (21333310012), we get a palindrome (42334643324).

The spelling of 21001333312 in words is "twenty-one billion, one million, three hundred thirty-three thousand, three hundred twelve".