21663043 has 8 divisors (see below), whose sum is σ = 22077968. Its totient is φ = 21250944.

The previous prime is 21663041. The next prime is 21663053. The reversal of 21663043 is 34036612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21663043 - 2¹ = 21663041 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21662999 and 21663017.

It is not an unprimeable number, because it can be changed into a prime (21663041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20455 + ... + 21487.

It is an arithmetic number, because the mean of its divisors is an integer number (2759746).

Almost surely, 2^21663043 is an apocalyptic number.

21663043 is a deficient number, since it is larger than the sum of its proper divisors (414925).

21663043 is a wasteful number, since it uses less digits than its factorization.

21663043 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1413.

The product of its (nonzero) digits is 2592, while the sum is 25.

The square root of 21663043 is about 4654.3574207403. The cubic root of 21663043 is about 278.7660109983.

Adding to 21663043 its reverse (34036612), we get a palindrome (55699655).

The spelling of 21663043 in words is "twenty-one million, six hundred sixty-three thousand, forty-three".