66975791 has 4 divisors (see below), whose sum is σ = 67919184. Its totient is φ = 66032400.

The previous prime is 66975787. The next prime is 66975803. The reversal of 66975791 is 19757966.

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 66975791 - 2² = 66975787 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 (66975721) 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 3 ways as a sum of consecutive naturals, for example, 471590 + ... + 471731.

It is an arithmetic number, because the mean of its divisors is an integer number (16979796).

Almost surely, 2^66975791 is an apocalyptic number.

66975791 is a deficient number, since it is larger than the sum of its proper divisors (943393).

66975791 is an equidigital number, since it uses as much as digits as its factorization.

66975791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 943392.

The product of its digits is 714420, while the sum is 50.

The square root of 66975791 is about 8183.8738382260. The cubic root of 66975791 is about 406.1058857346.

The spelling of 66975791 in words is "sixty-six million, nine hundred seventy-five thousand, seven hundred ninety-one".