20666217 has 32 divisors (see below), whose sum is σ = 32901120. Its totient is φ = 11373120.

The previous prime is 20666209. The next prime is 20666221. The reversal of 20666217 is 71266602.

It is not a de Polignac number, because 20666217 - 2³ = 20666209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20666257) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28384 + ... + 29102.

It is an arithmetic number, because the mean of its divisors is an integer number (1028160).

Almost surely, 2^20666217 is an apocalyptic number.

It is an amenable number.

20666217 is a deficient number, since it is larger than the sum of its proper divisors (12234903).

20666217 is a wasteful number, since it uses less digits than its factorization.

20666217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 813.

The product of its (nonzero) digits is 6048, while the sum is 30.

The square root of 20666217 is about 4546.0111086534. The cubic root of 20666217 is about 274.4228866905.

The spelling of 20666217 in words is "twenty million, six hundred sixty-six thousand, two hundred seventeen".