21005000003 has 4 divisors (see below), whose sum is σ = 22620769248. Its totient is φ = 19389230760.

The previous prime is 21004999979. The next prime is 21005000047. The reversal of 21005000003 is 30000050012.

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-21005000003 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21005000503) 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, 807884603 + ... + 807884628.

It is an arithmetic number, because the mean of its divisors is an integer number (5655192312).

Almost surely, 2^21005000003 is an apocalyptic number.

21005000003 is a deficient number, since it is larger than the sum of its proper divisors (1615769245).

21005000003 is a wasteful number, since it uses less digits than its factorization.

21005000003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1615769244.

The product of its (nonzero) digits is 30, while the sum is 11.

Adding to 21005000003 its reverse (30000050012), we get a palindrome (51005050015).

The spelling of 21005000003 in words is "twenty-one billion, five million, three", and thus it is an aban number and an uban number.