21043580544 has 256 divisors, whose sum is σ = 71207424000. Its totient is φ = 5993229312.

The previous prime is 21043580531. The next prime is 21043580581. The reversal of 21043580544 is 44508534012.

It is a happy number.

21043580544 is a `hidden beast` number, since 2 + 1 + 0 + 4 + 35 + 80 + 544 = 666.

It is a super-2 number, since 2×21043580544² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21043580499 and 21043580508.

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, 8683717 + ... + 8686139.

It is an arithmetic number, because the mean of its divisors is an integer number (278154000).

Almost surely, 2^21043580544 is an apocalyptic number.

21043580544 is a gapful number since it is divisible by the number (24) 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 21043580544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35603712000).

21043580544 is an abundant number, since it is smaller than the sum of its proper divisors (50163843456).

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

21043580544 is a wasteful number, since it uses less digits than its factorization.

21043580544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2812 (or 2794 counting only the distinct ones).

The product of its (nonzero) digits is 76800, while the sum is 36.

The spelling of 21043580544 in words is "twenty-one billion, forty-three million, five hundred eighty thousand, five hundred forty-four".