21717043 has 2 divisors, whose sum is σ = 21717044. Its totient is φ = 21717042.

The previous prime is 21717029. The next prime is 21717061. The reversal of 21717043 is 34071712.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21717043 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21716999 and 21717017.

It is not a weakly prime, because it can be changed into another prime (21717013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858521 + 10858522.

It is an arithmetic number, because the mean of its divisors is an integer number (10858522).

Almost surely, 2^21717043 is an apocalyptic number.

21717043 is a deficient number, since it is larger than the sum of its proper divisors (1).

21717043 is an equidigital number, since it uses as much as digits as its factorization.

21717043 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1176, while the sum is 25.

The square root of 21717043 is about 4660.1548257542. The cubic root of 21717043 is about 278.9974477655.

Adding to 21717043 its reverse (34071712), we get a palindrome (55788755).

The spelling of 21717043 in words is "twenty-one million, seven hundred seventeen thousand, forty-three".