21244303556 has 72 divisors (see below), whose sum is σ = 44506218624. Its totient is φ = 8691217920.

The previous prime is 21244303543. The next prime is 21244303559. The reversal of 21244303556 is 65530344212.

It is not an unprimeable number, because it can be changed into a prime (21244303559) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9345236 + ... + 9347508.

Almost surely, 2^21244303556 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21244303556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22253109312).

21244303556 is an abundant number, since it is smaller than the sum of its proper divisors (23261915068).

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

21244303556 is a wasteful number, since it uses less digits than its factorization.

21244303556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2961 (or 2936 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 35.

Adding to 21244303556 its reverse (65530344212), we get a palindrome (86774647768).

The spelling of 21244303556 in words is "twenty-one billion, two hundred forty-four million, three hundred three thousand, five hundred fifty-six".