66391071 has 8 divisors (see below), whose sum is σ = 88559280. Its totient is φ = 44241792.

The previous prime is 66390991. The next prime is 66391079. The reversal of 66391071 is 17019366.

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

It is not a de Polignac number, because 66391071 - 2⁷ = 66390943 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66391079) 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, 10071 + ... + 15303.

It is an arithmetic number, because the mean of its divisors is an integer number (11069910).

Almost surely, 2^66391071 is an apocalyptic number.

66391071 is a deficient number, since it is larger than the sum of its proper divisors (22168209).

66391071 is a wasteful number, since it uses less digits than its factorization.

66391071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9465.

The product of its (nonzero) digits is 6804, while the sum is 33.

The square root of 66391071 is about 8148.0716123510. The cubic root of 66391071 is about 404.9206184916.

The spelling of 66391071 in words is "sixty-six million, three hundred ninety-one thousand, seventy-one".