21317927 has 2 divisors, whose sum is σ = 21317928. Its totient is φ = 21317926.

The previous prime is 21317921. The next prime is 21317951. The reversal of 21317927 is 72971312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21317927 - 2¹⁰ = 21316903 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21317893 and 21317902.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21317921) 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, 10658963 + 10658964.

It is an arithmetic number, because the mean of its divisors is an integer number (10658964).

Almost surely, 2^21317927 is an apocalyptic number.

21317927 is a deficient number, since it is larger than the sum of its proper divisors (1).

21317927 is an equidigital number, since it uses as much as digits as its factorization.

21317927 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5292, while the sum is 32.

The square root of 21317927 is about 4617.1340677957. The cubic root of 21317927 is about 277.2777301940.

The spelling of 21317927 in words is "twenty-one million, three hundred seventeen thousand, nine hundred twenty-seven".