21659017 has 2 divisors, whose sum is σ = 21659018. Its totient is φ = 21659016.

The previous prime is 21658979. The next prime is 21659059. The reversal of 21659017 is 71095612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19501056 + 2157961 = 4416^2 + 1469^2 .

It is a cyclic number.

It is not a de Polignac number, because 21659017 - 2¹¹ = 21656969 is a prime.

It is a super-2 number, since 2×21659017² = 938226034812578, which contains 22 as substring.

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 21659017.

It is not a weakly prime, because it can be changed into another prime (21659117) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10829508 + 10829509.

It is an arithmetic number, because the mean of its divisors is an integer number (10829509).

Almost surely, 2^21659017 is an apocalyptic number.

It is an amenable number.

21659017 is a deficient number, since it is larger than the sum of its proper divisors (1).

21659017 is an equidigital number, since it uses as much as digits as its factorization.

21659017 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3780, while the sum is 31.

The square root of 21659017 is about 4653.9249027031. The cubic root of 21659017 is about 278.7487407023.

The spelling of 21659017 in words is "twenty-one million, six hundred fifty-nine thousand, seventeen".