21224004 has 12 divisors (see below), whose sum is σ = 49522704. Its totient is φ = 7074664.

The previous prime is 21224003. The next prime is 21224023. The reversal of 21224004 is 40042212.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (21224003) 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 3 ways as a sum of consecutive naturals, for example, 884322 + ... + 884345.

It is an arithmetic number, because the mean of its divisors is an integer number (4126892).

Almost surely, 2^21224004 is an apocalyptic number.

It is an amenable number.

21224004 is an abundant number, since it is smaller than the sum of its proper divisors (28298700).

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

21224004 is a wasteful number, since it uses less digits than its factorization.

21224004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1768674 (or 1768672 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 15.

The square root of 21224004 is about 4606.9517036757. The cubic root of 21224004 is about 276.8699185475.

Adding to 21224004 its reverse (40042212), we get a palindrome (61266216).

The spelling of 21224004 in words is "twenty-one million, two hundred twenty-four thousand, four".