66420217 has 4 divisors (see below), whose sum is σ = 68215396. Its totient is φ = 64625040.

The previous prime is 66420187. The next prime is 66420223. The reversal of 66420217 is 71202466.

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 60902416 + 5517801 = 7804^2 + 2349^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66420217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66420227) 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, 897534 + ... + 897607.

It is an arithmetic number, because the mean of its divisors is an integer number (17053849).

Almost surely, 2^66420217 is an apocalyptic number.

It is an amenable number.

66420217 is a deficient number, since it is larger than the sum of its proper divisors (1795179).

66420217 is a wasteful number, since it uses less digits than its factorization.

66420217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1795178.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 66420217 is about 8149.8599374468. The cubic root of 66420217 is about 404.9798638569.

The spelling of 66420217 in words is "sixty-six million, four hundred twenty thousand, two hundred seventeen".