21530003 has 8 divisors (see below), whose sum is σ = 23696496. Its totient is φ = 19398400.

The previous prime is 21529997. The next prime is 21530017. The reversal of 21530003 is 30003512.

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 21530003 - 2⁸ = 21529747 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21530003.

It is not an unprimeable number, because it can be changed into a prime (21530303) 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, 7418 + ... + 9903.

It is an arithmetic number, because the mean of its divisors is an integer number (2962062).

Almost surely, 2^21530003 is an apocalyptic number.

21530003 is a deficient number, since it is larger than the sum of its proper divisors (2166493).

21530003 is a wasteful number, since it uses less digits than its factorization.

21530003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17445.

The product of its (nonzero) digits is 90, while the sum is 14.

The square root of 21530003 is about 4640.0434265209. The cubic root of 21530003 is about 278.1941736454.

Adding to 21530003 its reverse (30003512), we get a palindrome (51533515).

The spelling of 21530003 in words is "twenty-one million, five hundred thirty thousand, three".