21042065 has 8 divisors (see below), whose sum is σ = 27546048. Its totient is φ = 15303280.

The previous prime is 21042059. The next prime is 21042089. The reversal of 21042065 is 56024012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21042065 - 2¹⁴ = 21025681 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 191237 + ... + 191346.

It is an arithmetic number, because the mean of its divisors is an integer number (3443256).

Almost surely, 2^21042065 is an apocalyptic number.

It is an amenable number.

21042065 is a deficient number, since it is larger than the sum of its proper divisors (6503983).

21042065 is a wasteful number, since it uses less digits than its factorization.

21042065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 382599.

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 21042065 is about 4587.1630666459. The cubic root of 21042065 is about 276.0765077055.

Adding to 21042065 its reverse (56024012), we get a palindrome (77066077).

The spelling of 21042065 in words is "twenty-one million, forty-two thousand, sixty-five".