21068717 has 2 divisors, whose sum is σ = 21068718. Its totient is φ = 21068716.

The previous prime is 21068669. The next prime is 21068741. The reversal of 21068717 is 71786012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20529961 + 538756 = 4531^2 + 734^2 .

It is a cyclic number.

It is not a de Polignac number, because 21068717 - 2⁶ = 21068653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21068317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10534358 + 10534359.

It is an arithmetic number, because the mean of its divisors is an integer number (10534359).

Almost surely, 2^21068717 is an apocalyptic number.

It is an amenable number.

21068717 is a deficient number, since it is larger than the sum of its proper divisors (1).

21068717 is an equidigital number, since it uses as much as digits as its factorization.

21068717 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4704, while the sum is 32.

The square root of 21068717 is about 4590.0672108369. The cubic root of 21068717 is about 276.1930185566.

It can be divided in two parts, 21068 and 717, that multiplied together give a triangular number (15105756 = T₅₄₉₆).

The spelling of 21068717 in words is "twenty-one million, sixty-eight thousand, seven hundred seventeen".