20663917 has 4 divisors (see below), whose sum is σ = 20696796. Its totient is φ = 20631040.

The previous prime is 20663861. The next prime is 20663927. The reversal of 20663917 is 71936602.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19527561 + 1136356 = 4419^2 + 1066^2 .

It is a cyclic number.

It is not a de Polignac number, because 20663917 - 2¹¹ = 20661869 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20663927) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15478 + ... + 16759.

It is an arithmetic number, because the mean of its divisors is an integer number (5174199).

Almost surely, 2^20663917 is an apocalyptic number.

It is an amenable number.

20663917 is a deficient number, since it is larger than the sum of its proper divisors (32879).

20663917 is an equidigital number, since it uses as much as digits as its factorization.

20663917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32878.

The product of its (nonzero) digits is 13608, while the sum is 34.

The square root of 20663917 is about 4545.7581325891. The cubic root of 20663917 is about 274.4127058874.

The spelling of 20663917 in words is "twenty million, six hundred sixty-three thousand, nine hundred seventeen".