21304144656 has 120 divisors (see below), whose sum is σ = 59993597664. Its totient is φ = 7057290240.

The previous prime is 21304144621. The next prime is 21304144669. The reversal of 21304144656 is 65644140312.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21304144656.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 24181336 + ... + 24182216.

Almost surely, 2^21304144656 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 21304144656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29996798832).

21304144656 is an abundant number, since it is smaller than the sum of its proper divisors (38689453008).

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

21304144656 is a wasteful number, since it uses less digits than its factorization.

21304144656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1749 (or 1740 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 36.

Adding to 21304144656 its reverse (65644140312), we get a palindrome (86948284968).

The spelling of 21304144656 in words is "twenty-one billion, three hundred four million, one hundred forty-four thousand, six hundred fifty-six".