21500221440 has 192 divisors, whose sum is σ = 70252116480. Its totient is φ = 5611028480.

The previous prime is 21500221439. The next prime is 21500221489. The reversal of 21500221440 is 4412200512.

It is a tau number, because it is divible by the number of its divisors (192).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1436395 + ... + 1451285.

It is an arithmetic number, because the mean of its divisors is an integer number (365896440).

Almost surely, 2^21500221440 is an apocalyptic number.

21500221440 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 21500221440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35126058240).

21500221440 is an abundant number, since it is smaller than the sum of its proper divisors (48751895040).

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

21500221440 is a wasteful number, since it uses less digits than its factorization.

21500221440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14968 (or 14948 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 21.

Adding to 21500221440 its reverse (4412200512), we get a palindrome (25912421952).

The spelling of 21500221440 in words is "twenty-one billion, five hundred million, two hundred twenty-one thousand, four hundred forty".