66643331 has 4 divisors (see below), whose sum is σ = 66667200. Its totient is φ = 66619464.

The previous prime is 66643319. The next prime is 66643333. The reversal of 66643331 is 13334666.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66643331 - 2¹⁸ = 66381187 is a prime.

It is a super-2 number, since 2×66643331² = 8882667133551122, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (66643333) 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, 7091 + ... + 13548.

It is an arithmetic number, because the mean of its divisors is an integer number (16666800).

Almost surely, 2^66643331 is an apocalyptic number.

66643331 is a deficient number, since it is larger than the sum of its proper divisors (23869).

66643331 is a wasteful number, since it uses less digits than its factorization.

66643331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23868.

The product of its digits is 23328, while the sum is 32.

The square root of 66643331 is about 8163.5366723008. The cubic root of 66643331 is about 405.4328167709.

Adding to 66643331 its reverse (13334666), we get a palindrome (79977997).

The spelling of 66643331 in words is "sixty-six million, six hundred forty-three thousand, three hundred thirty-one".