66633221 has 4 divisors (see below), whose sum is σ = 66898944. Its totient is φ = 66367500.

The previous prime is 66633179. The next prime is 66633223. The reversal of 66633221 is 12233666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12233666 = 2 ⋅6116833.

It is a cyclic number.

It is not a de Polignac number, because 66633221 - 2⁶ = 66633157 is a prime.

It is a super-2 number, since 2×66633221² = 8879972281669682, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66633223) 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, 132485 + ... + 132986.

It is an arithmetic number, because the mean of its divisors is an integer number (16724736).

Almost surely, 2^66633221 is an apocalyptic number.

It is an amenable number.

66633221 is a deficient number, since it is larger than the sum of its proper divisors (265723).

66633221 is a wasteful number, since it uses less digits than its factorization.

66633221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265722.

The product of its digits is 7776, while the sum is 29.

The square root of 66633221 is about 8162.9174318990. The cubic root of 66633221 is about 405.4123139288.

Adding to 66633221 its reverse (12233666), we get a palindrome (78866887).

The spelling of 66633221 in words is "sixty-six million, six hundred thirty-three thousand, two hundred twenty-one".