21312444403 has 4 divisors (see below), whose sum is σ = 21313453720. Its totient is φ = 21311435088.

The previous prime is 21312444367. The next prime is 21312444443. The reversal of 21312444403 is 30444421312.

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 21312444403 - 2²⁵ = 21278889971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21312444443) 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, 472293 + ... + 515446.

It is an arithmetic number, because the mean of its divisors is an integer number (5328363430).

Almost surely, 2^21312444403 is an apocalyptic number.

21312444403 is a deficient number, since it is larger than the sum of its proper divisors (1009317).

21312444403 is an equidigital number, since it uses as much as digits as its factorization.

21312444403 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1009316.

The product of its (nonzero) digits is 9216, while the sum is 28.

Adding to 21312444403 its reverse (30444421312), we get a palindrome (51756865715).

The spelling of 21312444403 in words is "twenty-one billion, three hundred twelve million, four hundred forty-four thousand, four hundred three".