21017065 has 16 divisors (see below), whose sum is σ = 25958016. Its totient is φ = 16329600.

The previous prime is 21017063. The next prime is 21017071. The reversal of 21017065 is 56071012.

It is not a de Polignac number, because 21017065 - 2¹ = 21017063 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21017063) 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 15 ways as a sum of consecutive naturals, for example, 25510 + ... + 26320.

It is an arithmetic number, because the mean of its divisors is an integer number (1622376).

Almost surely, 2^21017065 is an apocalyptic number.

It is an amenable number.

21017065 is a deficient number, since it is larger than the sum of its proper divisors (4940951).

21017065 is an equidigital number, since it uses as much as digits as its factorization.

21017065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 960.

The product of its (nonzero) digits is 420, while the sum is 22.

The square root of 21017065 is about 4584.4372609951. The cubic root of 21017065 is about 275.9671292156.

Adding to 21017065 its reverse (56071012), we get a palindrome (77088077).

The spelling of 21017065 in words is "twenty-one million, seventeen thousand, sixty-five".