21000803 has 2 divisors, whose sum is σ = 21000804. Its totient is φ = 21000802.

The previous prime is 21000779. The next prime is 21000821. The reversal of 21000803 is 30800012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21000803 - 2⁶ = 21000739 is a prime.

It is not a weakly prime, because it can be changed into another prime (21000823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500401 + 10500402.

It is an arithmetic number, because the mean of its divisors is an integer number (10500402).

Almost surely, 2^21000803 is an apocalyptic number.

21000803 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000803 is an equidigital number, since it uses as much as digits as its factorization.

21000803 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 21000803 is about 4582.6633086012. The cubic root of 21000803 is about 275.8959341268.

Adding to 21000803 its reverse (30800012), we get a palindrome (51800815).

The spelling of 21000803 in words is "twenty-one million, eight hundred three", and thus it is an aban number.