21004032 has 72 divisors (see below), whose sum is σ = 63903616. Its totient is φ = 5999616.

The previous prime is 21003937. The next prime is 21004043. The reversal of 21004032 is 23040012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21003999 and 21004017.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3423 + ... + 7329.

Almost surely, 2^21004032 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 21004032, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31951808).

21004032 is an abundant number, since it is smaller than the sum of its proper divisors (42899584).

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

21004032 is an equidigital number, since it uses as much as digits as its factorization.

21004032 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3933 (or 3919 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 12.

The square root of 21004032 is about 4583.0156011081. The cubic root of 21004032 is about 275.9100736229.

Adding to 21004032 its reverse (23040012), we get a palindrome (44044044).

The spelling of 21004032 in words is "twenty-one million, four thousand, thirty-two".