21004452 has 72 divisors (see below), whose sum is σ = 64262016. Its totient is φ = 5647104.

The previous prime is 21004447. The next prime is 21004457. The reversal of 21004452 is 25440012.

21004452 is a `hidden beast` number, since 210 + 0 + 4 + 452 = 666.

It is an interprime number because it is at equal distance from previous prime (21004447) and next prime (21004457).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21004457) 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, 1833 + ... + 6735.

It is an arithmetic number, because the mean of its divisors is an integer number (892528).

Almost surely, 2^21004452 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 21004452, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32131008).

21004452 is an abundant number, since it is smaller than the sum of its proper divisors (43257564).

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

21004452 is a wasteful number, since it uses less digits than its factorization.

21004452 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4937 (or 4932 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 21004452 is about 4583.0614222373. The cubic root of 21004452 is about 275.9119126580.

Adding to 21004452 its reverse (25440012), we get a palindrome (46444464).

The spelling of 21004452 in words is "twenty-one million, four thousand, four hundred fifty-two".