21521440000 has 180 divisors, whose sum is σ = 55425758080. Its totient is φ = 8328960000.

The previous prime is 21521439997. The next prime is 21521440001. The reversal of 21521440000 is 4412512.

It is a self number, because there is not a number n which added to its sum of digits gives 21521440000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521440001) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 4957831 + ... + 4962169.

Almost surely, 2^21521440000 is an apocalyptic number.

21521440000 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 21521440000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27712879040).

21521440000 is an abundant number, since it is smaller than the sum of its proper divisors (33904318080).

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

21521440000 is an frugal number, since it uses more digits than its factorization.

21521440000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4406 (or 4377 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 19.

Adding to 21521440000 its reverse (4412512), we get a palindrome (21525852512).

The spelling of 21521440000 in words is "twenty-one billion, five hundred twenty-one million, four hundred forty thousand".