21222504 has 24 divisors (see below), whose sum is σ = 57477810. Its totient is φ = 7074144.

The previous prime is 21222503. The next prime is 21222529. The reversal of 21222504 is 40522212.

It can be written as a sum of positive squares in only one way, i.e., 21178404 + 44100 = 4602^2 + 210^2 .

It is a tau number, because it is divible by the number of its divisors (24).

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 (21222503) 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 5 ways as a sum of consecutive naturals, for example, 147307 + ... + 147450.

Almost surely, 2^21222504 is an apocalyptic number.

21222504 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21222504 is an abundant number, since it is smaller than the sum of its proper divisors (36255306).

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

21222504 is a wasteful number, since it uses less digits than its factorization.

21222504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 294769 (or 294762 counting only the distinct ones).

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

The square root of 21222504 is about 4606.7889033469. The cubic root of 21222504 is about 276.8633958282.

Adding to 21222504 its reverse (40522212), we get a palindrome (61744716).

The spelling of 21222504 in words is "twenty-one million, two hundred twenty-two thousand, five hundred four".