20817965 has 16 divisors (see below), whose sum is σ = 28643328. Its totient is φ = 14228736.

The previous prime is 20817959. The next prime is 20817971. The reversal of 20817965 is 56971802.

It is an interprime number because it is at equal distance from previous prime (20817959) and next prime (20817971).

It is a cyclic number.

It is not a de Polignac number, because 20817965 - 2²⁰ = 19769389 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 in 15 ways as a sum of consecutive naturals, for example, 12629 + ... + 14181.

It is an arithmetic number, because the mean of its divisors is an integer number (1790208).

Almost surely, 2^20817965 is an apocalyptic number.

It is an amenable number.

20817965 is a deficient number, since it is larger than the sum of its proper divisors (7825363).

20817965 is a wasteful number, since it uses less digits than its factorization.

20817965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1948.

The product of its (nonzero) digits is 30240, while the sum is 38.

The square root of 20817965 is about 4562.6708187201. The cubic root of 20817965 is about 275.0929272724.

The spelling of 20817965 in words is "twenty million, eight hundred seventeen thousand, nine hundred sixty-five".