21423272 has 16 divisors (see below), whose sum is σ = 43258740. Its totient is φ = 9887616.

The previous prime is 21423271. The next prime is 21423287. The reversal of 21423272 is 27232412.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21031396 + 391876 = 4586^2 + 626^2 .

It is not an unprimeable number, because it can be changed into a prime (21423271) 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, 102893 + ... + 103100.

Almost surely, 2^21423272 is an apocalyptic number.

It is an amenable number.

21423272 is an abundant number, since it is smaller than the sum of its proper divisors (21835468).

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

21423272 is a wasteful number, since it uses less digits than its factorization.

21423272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206012 (or 206008 counting only the distinct ones).

The product of its digits is 1344, while the sum is 23.

The square root of 21423272 is about 4628.5280597615. The cubic root of 21423272 is about 277.7337132355.

Adding to 21423272 its reverse (27232412), we get a palindrome (48655684).

The spelling of 21423272 in words is "twenty-one million, four hundred twenty-three thousand, two hundred seventy-two".