21438563 has 8 divisors (see below), whose sum is σ = 21767616. Its totient is φ = 21112000.

The previous prime is 21438541. The next prime is 21438589. The reversal of 21438563 is 36583412.

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 21438563 - 2⁶ = 21438499 is a prime.

It is a super-2 number, since 2×21438563² = 919223967009938, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21438463) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23078 + ... + 23988.

It is an arithmetic number, because the mean of its divisors is an integer number (2720952).

Almost surely, 2^21438563 is an apocalyptic number.

21438563 is a deficient number, since it is larger than the sum of its proper divisors (329053).

21438563 is a wasteful number, since it uses less digits than its factorization.

21438563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1245.

The product of its digits is 17280, while the sum is 32.

The square root of 21438563 is about 4630.1795861500. The cubic root of 21438563 is about 277.7997756031.

The spelling of 21438563 in words is "twenty-one million, four hundred thirty-eight thousand, five hundred sixty-three".