21444555520 has 36 divisors (see below), whose sum is σ = 51366414960. Its totient is φ = 8577821696.

The previous prime is 21444555511. The next prime is 21444555521. The reversal of 21444555520 is 2555544412.

It is a super-2 number, since 2×21444555520² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21444555520.

It is not an unprimeable number, because it can be changed into a prime (21444555521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8375500 + ... + 8378059.

It is an arithmetic number, because the mean of its divisors is an integer number (1426844860).

Almost surely, 2^21444555520 is an apocalyptic number.

21444555520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21444555520 is an abundant number, since it is smaller than the sum of its proper divisors (29921859440).

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

21444555520 is an equidigital number, since it uses as much as digits as its factorization.

21444555520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16753580 (or 16753566 counting only the distinct ones).

The product of its (nonzero) digits is 160000, while the sum is 37.

The spelling of 21444555520 in words is "twenty-one billion, four hundred forty-four million, five hundred fifty-five thousand, five hundred twenty".