21173717 has 2 divisors, whose sum is σ = 21173718. Its totient is φ = 21173716.

The previous prime is 21173701. The next prime is 21173749. The reversal of 21173717 is 71737112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11895601 + 9278116 = 3449^2 + 3046^2 .

It is a cyclic number.

It is not a de Polignac number, because 21173717 - 2⁴ = 21173701 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21173717.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21173767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10586858 + 10586859.

It is an arithmetic number, because the mean of its divisors is an integer number (10586859).

Almost surely, 2^21173717 is an apocalyptic number.

It is an amenable number.

21173717 is a deficient number, since it is larger than the sum of its proper divisors (1).

21173717 is an equidigital number, since it uses as much as digits as its factorization.

21173717 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2058, while the sum is 29.

The square root of 21173717 is about 4601.4907367070. The cubic root of 21173717 is about 276.6510787818.

The spelling of 21173717 in words is "twenty-one million, one hundred seventy-three thousand, seven hundred seventeen".