21643033 has 12 divisors (see below), whose sum is σ = 23042880. Its totient is φ = 20324376.

The previous prime is 21643021. The next prime is 21643043. The reversal of 21643033 is 33034612.

It is a de Polignac number, because none of the positive numbers 2^k-21643033 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21642995 and 21643013.

It is not an unprimeable number, because it can be changed into a prime (21643043) 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 11 ways as a sum of consecutive naturals, for example, 60108 + ... + 60466.

It is an arithmetic number, because the mean of its divisors is an integer number (1920240).

Almost surely, 2^21643033 is an apocalyptic number.

It is an amenable number.

21643033 is a deficient number, since it is larger than the sum of its proper divisors (1399847).

21643033 is a wasteful number, since it uses less digits than its factorization.

21643033 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 564 (or 545 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 22.

The square root of 21643033 is about 4652.2073255606. The cubic root of 21643033 is about 278.6801531581.

Adding to 21643033 its reverse (33034612), we get a palindrome (54677645).

The spelling of 21643033 in words is "twenty-one million, six hundred forty-three thousand, thirty-three".