66943891 has 8 divisors (see below), whose sum is σ = 76637024. Its totient is φ = 57283200.

The previous prime is 66943879. The next prime is 66943913. The reversal of 66943891 is 19834966.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66943891 - 2⁹ = 66943379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66943391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3510 + ... + 12091.

It is an arithmetic number, because the mean of its divisors is an integer number (9579628).

Almost surely, 2^66943891 is an apocalyptic number.

66943891 is a deficient number, since it is larger than the sum of its proper divisors (9693133).

66943891 is a wasteful number, since it uses less digits than its factorization.

66943891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16221.

The product of its digits is 279936, while the sum is 46.

The square root of 66943891 is about 8181.9246513275. The cubic root of 66943891 is about 406.0414005684.

It can be divided in two parts, 6694 and 3891, that added together give a triangular number (10585 = T₁₄₅).

The spelling of 66943891 in words is "sixty-six million, nine hundred forty-three thousand, eight hundred ninety-one".