21003632 has 40 divisors (see below), whose sum is σ = 44111760. Its totient is φ = 9630720.

The previous prime is 21003601. The next prime is 21003637. The reversal of 21003632 is 23630012.

It is a self number, because there is not a number n which added to its sum of digits gives 21003632.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49919 + ... + 50337.

It is an arithmetic number, because the mean of its divisors is an integer number (1102794).

Almost surely, 2^21003632 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 21003632, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22055880).

21003632 is an abundant number, since it is smaller than the sum of its proper divisors (23108128).

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

21003632 is a wasteful number, since it uses less digits than its factorization.

21003632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 681 (or 675 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 17.

The square root of 21003632 is about 4582.9719615114. The cubic root of 21003632 is about 275.9083221381.

Adding to 21003632 its reverse (23630012), we get a palindrome (44633644).

The spelling of 21003632 in words is "twenty-one million, three thousand, six hundred thirty-two".