21330643 has 4 divisors (see below), whose sum is σ = 21378600. Its totient is φ = 21282688.

The previous prime is 21330641. The next prime is 21330649. The reversal of 21330643 is 34603312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21330643 - 2¹ = 21330641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21330641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23305 + ... + 24202.

It is an arithmetic number, because the mean of its divisors is an integer number (5344650).

Almost surely, 2^21330643 is an apocalyptic number.

21330643 is a deficient number, since it is larger than the sum of its proper divisors (47957).

21330643 is an equidigital number, since it uses as much as digits as its factorization.

21330643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47956.

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

The square root of 21330643 is about 4618.5109072081. The cubic root of 21330643 is about 277.3328506692.

Adding to 21330643 its reverse (34603312), we get a palindrome (55933955).

The spelling of 21330643 in words is "twenty-one million, three hundred thirty thousand, six hundred forty-three".