21007003 has 4 divisors (see below), whose sum is σ = 21041560. Its totient is φ = 20972448.

The previous prime is 21007001. The next prime is 21007013. The reversal of 21007003 is 30070012.

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 21007003 - 2¹ = 21007001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21007001) 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, 16350 + ... + 17587.

It is an arithmetic number, because the mean of its divisors is an integer number (5260390).

Almost surely, 2^21007003 is an apocalyptic number.

21007003 is a deficient number, since it is larger than the sum of its proper divisors (34557).

21007003 is an equidigital number, since it uses as much as digits as its factorization.

21007003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34556.

The product of its (nonzero) digits is 42, while the sum is 13.

The square root of 21007003 is about 4583.3397212077. The cubic root of 21007003 is about 275.9230820805.

Adding to 21007003 its reverse (30070012), we get a palindrome (51077015).

The spelling of 21007003 in words is "twenty-one million, seven thousand, three".