21018323 has 2 divisors, whose sum is σ = 21018324. Its totient is φ = 21018322.

The previous prime is 21018317. The next prime is 21018397. The reversal of 21018323 is 32381012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21018323 - 2¹⁶ = 20952787 is a prime.

It is a Sophie Germain prime.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 21018295 and 21018304.

It is not a weakly prime, because it can be changed into another prime (21018523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10509161 + 10509162.

It is an arithmetic number, because the mean of its divisors is an integer number (10509162).

Almost surely, 2^21018323 is an apocalyptic number.

21018323 is a deficient number, since it is larger than the sum of its proper divisors (1).

21018323 is an equidigital number, since it uses as much as digits as its factorization.

21018323 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21018323 is about 4584.5744622593. The cubic root of 21018323 is about 275.9726352131.

Adding to 21018323 its reverse (32381012), we get a palindrome (53399335).

The spelling of 21018323 in words is "twenty-one million, eighteen thousand, three hundred twenty-three".