21643252 has 6 divisors (see below), whose sum is σ = 37875698. Its totient is φ = 10821624.

The previous prime is 21643247. The next prime is 21643267. The reversal of 21643252 is 25234612.

It can be written as a sum of positive squares in only one way, i.e., 18352656 + 3290596 = 4284^2 + 1814^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2705403 + ... + 2705410.

Almost surely, 2^21643252 is an apocalyptic number.

It is an amenable number.

21643252 is a deficient number, since it is larger than the sum of its proper divisors (16232446).

21643252 is a wasteful number, since it uses less digits than its factorization.

21643252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5410817 (or 5410815 counting only the distinct ones).

The product of its digits is 2880, while the sum is 25.

The square root of 21643252 is about 4652.2308627152. The cubic root of 21643252 is about 278.6810931180.

Adding to 21643252 its reverse (25234612), we get a palindrome (46877864).

The spelling of 21643252 in words is "twenty-one million, six hundred forty-three thousand, two hundred fifty-two".