21240204203 has 4 divisors (see below), whose sum is σ = 21240530088. Its totient is φ = 21239878320.

The previous prime is 21240204149. The next prime is 21240204229. The reversal of 21240204203 is 30240204212.

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 21240204203 - 2²⁸ = 20971768747 is a prime.

It is a super-2 number, since 2×21240204203² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21240204803) 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, 27833 + ... + 207978.

It is an arithmetic number, because the mean of its divisors is an integer number (5310132522).

Almost surely, 2^21240204203 is an apocalyptic number.

21240204203 is a deficient number, since it is larger than the sum of its proper divisors (325885).

21240204203 is an equidigital number, since it uses as much as digits as its factorization.

21240204203 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 325884.

The product of its (nonzero) digits is 768, while the sum is 20.

Adding to 21240204203 its reverse (30240204212), we get a palindrome (51480408415).

Subtracting 21240204203 from its reverse (30240204212), we obtain a palindrome (9000000009).

The spelling of 21240204203 in words is "twenty-one billion, two hundred forty million, two hundred four thousand, two hundred three".