21000103 has 2 divisors, whose sum is σ = 21000104. Its totient is φ = 21000102.

The previous prime is 21000097. The next prime is 21000121. The reversal of 21000103 is 30100012.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21000103 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21000143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500051 + 10500052.

It is an arithmetic number, because the mean of its divisors is an integer number (10500052).

Almost surely, 2^21000103 is an apocalyptic number.

21000103 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000103 is an equidigital number, since it uses as much as digits as its factorization.

21000103 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6, while the sum is 7.

The square root of 21000103 is about 4582.5869331634. The cubic root of 21000103 is about 275.8928686996.

Adding to 21000103 its reverse (30100012), we get a palindrome (51100115).

Subtracting 21000103 from its reverse (30100012), we obtain a palindrome (9099909).

The spelling of 21000103 in words is "twenty-one million, one hundred three", and thus it is an aban number.