21533203 has 8 divisors (see below), whose sum is σ = 22921488. Its totient is φ = 20158464.

The previous prime is 21533177. The next prime is 21533207. The reversal of 21533203 is 30233512.

21533203 is a nontrivial binomial coefficient, being equal to C(6563, 2).

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

It is a de Polignac number, because none of the positive numbers 2^k-21533203 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21533207) 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, 1 + ... + 6562.

It is an arithmetic number, because the mean of its divisors is an integer number (2865186).

Almost surely, 2^21533203 is an apocalyptic number.

21533203 is the 6562-nd triangular number.

21533203 is the 2188-th centered nonagonal number.

21533203 is a deficient number, since it is larger than the sum of its proper divisors (1388285).

21533203 is a wasteful number, since it uses less digits than its factorization.

21533203 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6773.

The product of its (nonzero) digits is 540, while the sum is 19.

The square root of 21533203 is about 4640.3882380680. The cubic root of 21533203 is about 278.2079556106.

Adding to 21533203 its reverse (30233512), we get a palindrome (51766715).

It can be divided in two parts, 21533 and 203, that added together give a triangular number (21736 = T₂₀₈).

The spelling of 21533203 in words is "twenty-one million, five hundred thirty-three thousand, two hundred three".