66380221 has 4 divisors (see below), whose sum is σ = 67632732. Its totient is φ = 65127712.

The previous prime is 66380219. The next prime is 66380239. The reversal of 66380221 is 12208366.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12208366 = 2 ⋅6104183.

It can be written as a sum of positive squares in 2 ways, for example, as 45091225 + 21288996 = 6715^2 + 4614^2 .

It is a cyclic number.

It is not a de Polignac number, because 66380221 - 2¹ = 66380219 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66380221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66381221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 626176 + ... + 626281.

It is an arithmetic number, because the mean of its divisors is an integer number (16908183).

Almost surely, 2^66380221 is an apocalyptic number.

It is an amenable number.

66380221 is a deficient number, since it is larger than the sum of its proper divisors (1252511).

66380221 is a wasteful number, since it uses less digits than its factorization.

66380221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1252510.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 66380221 is about 8147.4057834381. The cubic root of 66380221 is about 404.8985591595.

Adding to 66380221 its reverse (12208366), we get a palindrome (78588587).

The spelling of 66380221 in words is "sixty-six million, three hundred eighty thousand, two hundred twenty-one".