21443253 has 16 divisors (see below), whose sum is σ = 30957696. Its totient is φ = 13124160.

The previous prime is 21443221. The next prime is 21443263. The reversal of 21443253 is 35234412.

It is not a de Polignac number, because 21443253 - 2⁵ = 21443221 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21443203) 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 15 ways as a sum of consecutive naturals, for example, 6288 + ... + 9078.

It is an arithmetic number, because the mean of its divisors is an integer number (1934856).

Almost surely, 2^21443253 is an apocalyptic number.

It is an amenable number.

21443253 is a deficient number, since it is larger than the sum of its proper divisors (9514443).

21443253 is a wasteful number, since it uses less digits than its factorization.

21443253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3004.

The product of its digits is 2880, while the sum is 24.

The square root of 21443253 is about 4630.6860182915. The cubic root of 21443253 is about 277.8200317174.

Adding to 21443253 its reverse (35234412), we get a palindrome (56677665).

The spelling of 21443253 in words is "twenty-one million, four hundred forty-three thousand, two hundred fifty-three".