21017017 has 4 divisors (see below), whose sum is σ = 24019456. Its totient is φ = 18014580.

The previous prime is 21016997. The next prime is 21017027. The reversal of 21017017 is 71071012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21017017 - 2¹⁹ = 20492729 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21016985 and 21017003.

It is not an unprimeable number, because it can be changed into a prime (21017027) 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 in 3 ways as a sum of consecutive naturals, for example, 1501209 + ... + 1501222.

It is an arithmetic number, because the mean of its divisors is an integer number (6004864).

Almost surely, 2^21017017 is an apocalyptic number.

It is an amenable number.

21017017 is a deficient number, since it is larger than the sum of its proper divisors (3002439).

21017017 is an equidigital number, since it uses as much as digits as its factorization.

21017017 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3002438.

The product of its (nonzero) digits is 98, while the sum is 19.

The square root of 21017017 is about 4584.4320258894. The cubic root of 21017017 is about 275.9669191255.

Adding to 21017017 its reverse (71071012), we get a palindrome (92088029).

The spelling of 21017017 in words is "twenty-one million, seventeen thousand, seventeen".