66585991 has 8 divisors (see below), whose sum is σ = 70582320. Its totient is φ = 62598528.

The previous prime is 66585979. The next prime is 66586027. The reversal of 66585991 is 19958566.

66585991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 66585991 - 2⁷ = 66585863 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66585091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19300 + ... + 22486.

It is an arithmetic number, because the mean of its divisors is an integer number (8822790).

Almost surely, 2^66585991 is an apocalyptic number.

66585991 is a deficient number, since it is larger than the sum of its proper divisors (3996329).

66585991 is a wasteful number, since it uses less digits than its factorization.

66585991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4433.

The product of its digits is 583200, while the sum is 49.

The square root of 66585991 is about 8160.0239582982. The cubic root of 66585991 is about 405.3165051162.

It can be divided in two parts, 66585 and 991, that added together give a palindrome (67576).

The spelling of 66585991 in words is "sixty-six million, five hundred eighty-five thousand, nine hundred ninety-one".