21204312224 has 36 divisors (see below), whose sum is σ = 42378650874. Its totient is φ = 10443844224.

The previous prime is 21204312223. The next prime is 21204312271. The reversal of 21204312224 is 42221340212.

It can be written as a sum of positive squares in only one way, i.e., 17884247824 + 3320064400 = 133732^2 + 57620^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21204312224.

It is not an unprimeable number, because it can be changed into a prime (21204312223) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 69842 + ... + 217454.

Almost surely, 2^21204312224 is an apocalyptic number.

It is an amenable number.

21204312224 is a deficient number, since it is larger than the sum of its proper divisors (21174338650).

21204312224 is an equidigital number, since it uses as much as digits as its factorization.

21204312224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147757 (or 147682 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 23.

Adding to 21204312224 its reverse (42221340212), we get a palindrome (63425652436).

The spelling of 21204312224 in words is "twenty-one billion, two hundred four million, three hundred twelve thousand, two hundred twenty-four".