66864217 has 16 divisors (see below), whose sum is σ = 79978752. Its totient is φ = 54699840.

The previous prime is 66864209. The next prime is 66864223. The reversal of 66864217 is 71246866.

It is a cyclic number.

It is not a de Polignac number, because 66864217 - 2³ = 66864209 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66864217.

It is not an unprimeable number, because it can be changed into a prime (66864617) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11292 + ... + 16162.

It is an arithmetic number, because the mean of its divisors is an integer number (4998672).

Almost surely, 2^66864217 is an apocalyptic number.

It is an amenable number.

66864217 is a deficient number, since it is larger than the sum of its proper divisors (13114535).

66864217 is a wasteful number, since it uses less digits than its factorization.

66864217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4968.

The product of its digits is 96768, while the sum is 40.

The square root of 66864217 is about 8177.0542984623. The cubic root of 66864217 is about 405.8802517574.

It can be divided in two parts, 66864 and 217, that added together give a square (67081 = 259²).

The spelling of 66864217 in words is "sixty-six million, eight hundred sixty-four thousand, two hundred seventeen".