666841831 has 4 divisors (see below), whose sum is σ = 667015992. Its totient is φ = 666667672.

The previous prime is 666841811. The next prime is 666841843. The reversal of 666841831 is 138148666.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 138148666 = 2 ⋅69074333.

It is a cyclic number.

It is not a de Polignac number, because 666841831 - 2¹¹ = 666839783 is a prime.

It is a super-3 number, since 3×666841831³ (a number of 27 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666841801) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 81205 + ... + 89038.

It is an arithmetic number, because the mean of its divisors is an integer number (166753998).

Almost surely, 2^666841831 is an apocalyptic number.

666841831 is a deficient number, since it is larger than the sum of its proper divisors (174161).

666841831 is a wasteful number, since it uses less digits than its factorization.

666841831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174160.

The product of its digits is 165888, while the sum is 43.

The square root of 666841831 is about 25823.2807946628. The cubic root of 666841831 is about 873.6569681062.

The spelling of 666841831 in words is "six hundred sixty-six million, eight hundred forty-one thousand, eight hundred thirty-one".