21530163 has 4 divisors (see below), whose sum is σ = 28706888. Its totient is φ = 14353440.

The previous prime is 21530161. The next prime is 21530227. The reversal of 21530163 is 36103512.

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

It is not a de Polignac number, because 21530163 - 2¹ = 21530161 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21530161) 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, 3588358 + ... + 3588363.

It is an arithmetic number, because the mean of its divisors is an integer number (7176722).

Almost surely, 2^21530163 is an apocalyptic number.

21530163 is a deficient number, since it is larger than the sum of its proper divisors (7176725).

21530163 is an equidigital number, since it uses as much as digits as its factorization.

21530163 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7176724.

The product of its (nonzero) digits is 540, while the sum is 21.

The square root of 21530163 is about 4640.0606677068. The cubic root of 21530163 is about 278.1948627761.

Adding to 21530163 its reverse (36103512), we get a palindrome (57633675).

The spelling of 21530163 in words is "twenty-one million, five hundred thirty thousand, one hundred sixty-three".