21717089 has 2 divisors, whose sum is σ = 21717090. Its totient is φ = 21717088.

The previous prime is 21717071. The next prime is 21717119. The reversal of 21717089 is 98071712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21529600 + 187489 = 4640^2 + 433^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21717089 is a prime.

It is not a weakly prime, because it can be changed into another prime (21717029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858544 + 10858545.

It is an arithmetic number, because the mean of its divisors is an integer number (10858545).

Almost surely, 2^21717089 is an apocalyptic number.

It is an amenable number.

21717089 is a deficient number, since it is larger than the sum of its proper divisors (1).

21717089 is an equidigital number, since it uses as much as digits as its factorization.

21717089 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 21717089 is about 4660.1597612099. The cubic root of 21717089 is about 278.9976447517.

The spelling of 21717089 in words is "twenty-one million, seven hundred seventeen thousand, eighty-nine".