21163643 has 2 divisors, whose sum is σ = 21163644. Its totient is φ = 21163642.

The previous prime is 21163627. The next prime is 21163687. The reversal of 21163643 is 34636112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21163643 - 2⁴ = 21163627 is a prime.

It is not a weakly prime, because it can be changed into another prime (21163603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10581821 + 10581822.

It is an arithmetic number, because the mean of its divisors is an integer number (10581822).

Almost surely, 2^21163643 is an apocalyptic number.

21163643 is a deficient number, since it is larger than the sum of its proper divisors (1).

21163643 is an equidigital number, since it uses as much as digits as its factorization.

21163643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2592, while the sum is 26.

The square root of 21163643 is about 4600.3959612190. The cubic root of 21163643 is about 276.6071969403.

Adding to 21163643 its reverse (34636112), we get a palindrome (55799755).

The spelling of 21163643 in words is "twenty-one million, one hundred sixty-three thousand, six hundred forty-three".