666791 has 8 divisors (see below), whose sum is σ = 718704. Its totient is φ = 616320.

The previous prime is 666773. The next prime is 666811. The reversal of 666791 is 197666.

It is a happy number.

666791 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 666791 - 2⁶ = 666727 is a prime.

It is a super-2 number, since 2×666791² = 889220475362, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 9 and base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666751) 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, 716 + ... + 1358.

It is an arithmetic number, because the mean of its divisors is an integer number (89838).

2⁶⁶⁶⁷⁹¹ is an apocalyptic number.

666791 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

666791 is a deficient number, since it is larger than the sum of its proper divisors (51913).

666791 is a wasteful number, since it uses less digits than its factorization.

666791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 721.

The product of its digits is 13608, while the sum is 35.

The square root of 666791 is about 816.5727156843. The cubic root of 666791 is about 87.3634768946.

The spelling of 666791 in words is "six hundred sixty-six thousand, seven hundred ninety-one".