21581484480 has 280 divisors, whose sum is σ = 79419114720. Its totient is φ = 5556418560.

The previous prime is 21581484473. The next prime is 21581484481. The reversal of 21581484480 is 8448418512.

21581484480 is a `hidden beast` number, since 2 + 15 + 81 + 4 + 84 + 480 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21581484481) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 737325 + ... + 766035.

Almost surely, 2^21581484480 is an apocalyptic number.

21581484480 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 21581484480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39709557360).

21581484480 is an abundant number, since it is smaller than the sum of its proper divisors (57837630240).

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

21581484480 is a wasteful number, since it uses less digits than its factorization.

21581484480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28769 (or 28750 counting only the distinct ones).

The product of its (nonzero) digits is 327680, while the sum is 45.

The spelling of 21581484480 in words is "twenty-one billion, five hundred eighty-one million, four hundred eighty-four thousand, four hundred eighty".