21531002203 has 4 divisors (see below), whose sum is σ = 21544286368. Its totient is φ = 21517718040.

The previous prime is 21531002201. The next prime is 21531002239. The reversal of 21531002203 is 30220013512.

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

It is a cyclic number.

It is not a de Polignac number, because 21531002203 - 2¹ = 21531002201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21531002201) 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, 6639651 + ... + 6642892.

It is an arithmetic number, because the mean of its divisors is an integer number (5386071592).

Almost surely, 2^21531002203 is an apocalyptic number.

21531002203 is a deficient number, since it is larger than the sum of its proper divisors (13284165).

21531002203 is a wasteful number, since it uses less digits than its factorization.

21531002203 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13284164.

The product of its (nonzero) digits is 360, while the sum is 19.

Adding to 21531002203 its reverse (30220013512), we get a palindrome (51751015715).

The spelling of 21531002203 in words is "twenty-one billion, five hundred thirty-one million, two thousand, two hundred three".