66991143 has 8 divisors (see below), whose sum is σ = 89362800. Its totient is φ = 44640128.

The previous prime is 66991117. The next prime is 66991163. The reversal of 66991143 is 34119966.

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 66991143 - 2⁹ = 66990631 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66991163) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5653 + ... + 12881.

It is an arithmetic number, because the mean of its divisors is an integer number (11170350).

Almost surely, 2^66991143 is an apocalyptic number.

66991143 is a deficient number, since it is larger than the sum of its proper divisors (22371657).

66991143 is a wasteful number, since it uses less digits than its factorization.

66991143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10321.

The product of its digits is 34992, while the sum is 39.

The square root of 66991143 is about 8184.8117266068. The cubic root of 66991143 is about 406.1369121755.

The spelling of 66991143 in words is "sixty-six million, nine hundred ninety-one thousand, one hundred forty-three".