21316723 has 2 divisors, whose sum is σ = 21316724. Its totient is φ = 21316722.

The previous prime is 21316721. The next prime is 21316739. The reversal of 21316723 is 32761312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21316723 - 2¹ = 21316721 is a prime.

Together with 21316721, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21316721) 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, 10658361 + 10658362.

It is an arithmetic number, because the mean of its divisors is an integer number (10658362).

Almost surely, 2^21316723 is an apocalyptic number.

21316723 is a deficient number, since it is larger than the sum of its proper divisors (1).

21316723 is an equidigital number, since it uses as much as digits as its factorization.

21316723 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1512, while the sum is 25.

The square root of 21316723 is about 4617.0036820431. The cubic root of 21316723 is about 277.2725100387.

The spelling of 21316723 in words is "twenty-one million, three hundred sixteen thousand, seven hundred twenty-three".