21445240320 has 640 divisors, whose sum is σ = 87994368000. Its totient is φ = 4849238016.

The previous prime is 21445240307. The next prime is 21445240339. The reversal of 21445240320 is 2304254412.

21445240320 is a `hidden beast` number, since 214 + 45 + 2 + 403 + 2 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (640).

It is a super-3 number, since 3×21445240320³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 61447506 + ... + 61447854.

It is an arithmetic number, because the mean of its divisors is an integer number (137491200).

Almost surely, 2^21445240320 is an apocalyptic number.

21445240320 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 21445240320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43997184000).

21445240320 is an abundant number, since it is smaller than the sum of its proper divisors (66549127680).

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

21445240320 is a wasteful number, since it uses less digits than its factorization.

21445240320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 515 (or 493 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 27.

Adding to 21445240320 its reverse (2304254412), we get a palindrome (23749494732).

The spelling of 21445240320 in words is "twenty-one billion, four hundred forty-five million, two hundred forty thousand, three hundred twenty".