20817845 has 8 divisors (see below), whose sum is σ = 25224576. Its totient is φ = 16492176.

The previous prime is 20817827. The next prime is 20817857. The reversal of 20817845 is 54871802.

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

It is a cyclic number.

It is not a de Polignac number, because 20817845 - 2¹⁰ = 20816821 is a prime.

It is a Duffinian number.

It is a congruent 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, 19697 + ... + 20726.

It is an arithmetic number, because the mean of its divisors is an integer number (3153072).

Almost surely, 2^20817845 is an apocalyptic number.

It is an amenable number.

20817845 is a deficient number, since it is larger than the sum of its proper divisors (4406731).

20817845 is a wasteful number, since it uses less digits than its factorization.

20817845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40531.

The product of its (nonzero) digits is 17920, while the sum is 35.

The square root of 20817845 is about 4562.6576685086. The cubic root of 20817845 is about 275.0923987031.

The spelling of 20817845 in words is "twenty million, eight hundred seventeen thousand, eight hundred forty-five".