21030403 has 2 divisors, whose sum is σ = 21030404. Its totient is φ = 21030402.

The previous prime is 21030389. The next prime is 21030463. The reversal of 21030403 is 30403012.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21030403 is a prime.

It is not a weakly prime, because it can be changed into another prime (21030463) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10515201 + 10515202.

It is an arithmetic number, because the mean of its divisors is an integer number (10515202).

Almost surely, 2^21030403 is an apocalyptic number.

21030403 is a deficient number, since it is larger than the sum of its proper divisors (1).

21030403 is an equidigital number, since it uses as much as digits as its factorization.

21030403 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 13.

The square root of 21030403 is about 4585.8917344394. The cubic root of 21030403 is about 276.0254956144.

Adding to 21030403 its reverse (30403012), we get a palindrome (51433415).

The spelling of 21030403 in words is "twenty-one million, thirty thousand, four hundred three".