21215004440 has 128 divisors (see below), whose sum is σ = 55454976000. Its totient is φ = 7154155008.

The previous prime is 21215004407. The next prime is 21215004467. The reversal of 21215004440 is 4440051212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6258266 + ... + 6261654.

It is an arithmetic number, because the mean of its divisors is an integer number (433242000).

Almost surely, 2^21215004440 is an apocalyptic number.

21215004440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21215004440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27727488000).

21215004440 is an abundant number, since it is smaller than the sum of its proper divisors (34239971560).

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

21215004440 is a wasteful number, since it uses less digits than its factorization.

21215004440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3769 (or 3765 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 23.

Adding to 21215004440 its reverse (4440051212), we get a palindrome (25655055652).

The spelling of 21215004440 in words is "twenty-one billion, two hundred fifteen million, four thousand, four hundred forty".