21423563 has 8 divisors (see below), whose sum is σ = 24514560. Its totient is φ = 18340200.

The previous prime is 21423559. The next prime is 21423581. The reversal of 21423563 is 36532412.

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 21423563 - 2² = 21423559 is a prime.

It is a super-2 number, since 2×21423563² = 917938103229938, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21423533) 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, 6728 + ... + 9386.

It is an arithmetic number, because the mean of its divisors is an integer number (3064320).

Almost surely, 2^21423563 is an apocalyptic number.

21423563 is a deficient number, since it is larger than the sum of its proper divisors (3090997).

21423563 is a wasteful number, since it uses less digits than its factorization.

21423563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3817.

The product of its digits is 4320, while the sum is 26.

The square root of 21423563 is about 4628.5594951345. The cubic root of 21423563 is about 277.7349707487.

Adding to 21423563 its reverse (36532412), we get a palindrome (57955975).

The spelling of 21423563 in words is "twenty-one million, four hundred twenty-three thousand, five hundred sixty-three".