21003403243 has 4 divisors (see below), whose sum is σ = 21080906848. Its totient is φ = 20925899640.

The previous prime is 21003403237. The next prime is 21003403261. The reversal of 21003403243 is 34230430012.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21003403243 is a prime.

It is a super-2 number, since 2×21003403243² (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 (21003403273) 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, 38751396 + ... + 38751937.

It is an arithmetic number, because the mean of its divisors is an integer number (5270226712).

Almost surely, 2^21003403243 is an apocalyptic number.

21003403243 is a deficient number, since it is larger than the sum of its proper divisors (77503605).

21003403243 is an equidigital number, since it uses as much as digits as its factorization.

21003403243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77503604.

The product of its (nonzero) digits is 1728, while the sum is 22.

Adding to 21003403243 its reverse (34230430012), we get a palindrome (55233833255).

The spelling of 21003403243 in words is "twenty-one billion, three million, four hundred three thousand, two hundred forty-three".