21042803 has 2 divisors, whose sum is σ = 21042804. Its totient is φ = 21042802.

The previous prime is 21042739. The next prime is 21042829. The reversal of 21042803 is 30824012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21042803 - 2⁶ = 21042739 is a prime.

It is not a weakly prime, because it can be changed into another prime (21042863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521401 + 10521402.

It is an arithmetic number, because the mean of its divisors is an integer number (10521402).

Almost surely, 2^21042803 is an apocalyptic number.

21042803 is a deficient number, since it is larger than the sum of its proper divisors (1).

21042803 is an equidigital number, since it uses as much as digits as its factorization.

21042803 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 21042803 is about 4587.2435078160. The cubic root of 21042803 is about 276.0797352417.

Adding to 21042803 its reverse (30824012), we get a palindrome (51866815).

The spelling of 21042803 in words is "twenty-one million, forty-two thousand, eight hundred three".