21271903 has 2 divisors, whose sum is σ = 21271904. Its totient is φ = 21271902.

The previous prime is 21271891. The next prime is 21271931. The reversal of 21271903 is 30917212.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21271903 is a prime.

It is equal to p_1346038 and since 21271903 and 1346038 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21271973) 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, 10635951 + 10635952.

It is an arithmetic number, because the mean of its divisors is an integer number (10635952).

Almost surely, 2^21271903 is an apocalyptic number.

21271903 is a deficient number, since it is larger than the sum of its proper divisors (1).

21271903 is an equidigital number, since it uses as much as digits as its factorization.

21271903 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 21271903 is about 4612.1473306910. The cubic root of 21271903 is about 277.0780449716.

The spelling of 21271903 in words is "twenty-one million, two hundred seventy-one thousand, nine hundred three".