66330221 has 4 divisors (see below), whose sum is σ = 68617500. Its totient is φ = 64042944.

The previous prime is 66330211. The next prime is 66330239. The reversal of 66330221 is 12203366.

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 50608996 + 15721225 = 7114^2 + 3965^2 .

It is a cyclic number.

It is not a de Polignac number, because 66330221 - 2⁶ = 66330157 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66330211) 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, 1143596 + ... + 1143653.

It is an arithmetic number, because the mean of its divisors is an integer number (17154375).

Almost surely, 2^66330221 is an apocalyptic number.

It is an amenable number.

66330221 is a deficient number, since it is larger than the sum of its proper divisors (2287279).

66330221 is a wasteful number, since it uses less digits than its factorization.

66330221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2287278.

The product of its (nonzero) digits is 1296, while the sum is 23.

The square root of 66330221 is about 8144.3367440204. The cubic root of 66330221 is about 404.7968721767.

Adding to 66330221 its reverse (12203366), we get a palindrome (78533587).

The spelling of 66330221 in words is "sixty-six million, three hundred thirty thousand, two hundred twenty-one".