21443004 has 72 divisors (see below), whose sum is σ = 59662512. Its totient is φ = 6439680.

The previous prime is 21443003. The next prime is 21443033. The reversal of 21443004 is 40034412.

Added to its reverse (40034412) it gives a triangular number (61477416 = T₁₁₀₈₈).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21443003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 68352 + ... + 68664.

It is an arithmetic number, because the mean of its divisors is an integer number (828646).

Almost surely, 2^21443004 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 21443004, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29831256).

21443004 is an abundant number, since it is smaller than the sum of its proper divisors (38219508).

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

21443004 is a wasteful number, since it uses less digits than its factorization.

21443004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 507 (or 502 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 21443004 is about 4630.6591323482. The cubic root of 21443004 is about 277.8189563605.

Adding to 21443004 its reverse (40034412), we get a palindrome (61477416).

The spelling of 21443004 in words is "twenty-one million, four hundred forty-three thousand, four".