21023017 has 2 divisors, whose sum is σ = 21023018. Its totient is φ = 21023016.

The previous prime is 21023003. The next prime is 21023047. The reversal of 21023017 is 71032012.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11634921 + 9388096 = 3411^2 + 3064^2 .

It is a cyclic number.

It is not a de Polignac number, because 21023017 - 2⁷ = 21022889 is a prime.

It is not a weakly prime, because it can be changed into another prime (21023047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10511508 + 10511509.

It is an arithmetic number, because the mean of its divisors is an integer number (10511509).

Almost surely, 2^21023017 is an apocalyptic number.

It is an amenable number.

21023017 is a deficient number, since it is larger than the sum of its proper divisors (1).

21023017 is an equidigital number, since it uses as much as digits as its factorization.

21023017 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 84, while the sum is 16.

The square root of 21023017 is about 4585.0863677798. The cubic root of 21023017 is about 275.9931779102.

Adding to 21023017 its reverse (71032012), we get a palindrome (92055029).

The spelling of 21023017 in words is "twenty-one million, twenty-three thousand, seventeen".