21224643 has 16 divisors (see below), whose sum is σ = 31708416. Its totient is φ = 12515040.

The previous prime is 21224633. The next prime is 21224647. The reversal of 21224643 is 34642212.

It is not a de Polignac number, because 21224643 - 2⁶ = 21224579 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21224647) 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, 7471 + ... + 9912.

It is an arithmetic number, because the mean of its divisors is an integer number (1981776).

Almost surely, 2^21224643 is an apocalyptic number.

21224643 is a deficient number, since it is larger than the sum of its proper divisors (10483773).

21224643 is a wasteful number, since it uses less digits than its factorization.

21224643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17434.

The product of its digits is 2304, while the sum is 24.

The square root of 21224643 is about 4607.0210548683. The cubic root of 21224643 is about 276.8726971326.

Adding to 21224643 its reverse (34642212), we get a palindrome (55866855).

Subtracting 21224643 from its reverse (34642212), we obtain a square (13417569 = 3663²).

The spelling of 21224643 in words is "twenty-one million, two hundred twenty-four thousand, six hundred forty-three".