666931 has 8 divisors (see below), whose sum is σ = 705024. Its totient is φ = 629640.

The previous prime is 666929. The next prime is 666937. The reversal of 666931 is 139666.

666931 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 666931 - 2¹ = 666929 is a prime.

It is a super-2 number, since 2×666931² = 889593917522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 666893 and 666902.

It is not an unprimeable number, because it can be changed into a prime (666937) 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, 2326 + ... + 2596.

It is an arithmetic number, because the mean of its divisors is an integer number (88128).

2⁶⁶⁶⁹³¹ is an apocalyptic number.

666931 is the 517-th centered pentagonal number.

666931 is a deficient number, since it is larger than the sum of its proper divisors (38093).

666931 is a wasteful number, since it uses less digits than its factorization.

666931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 401.

The product of its digits is 5832, while the sum is 31.

The square root of 666931 is about 816.6584353327. The cubic root of 666931 is about 87.3695907698.

It can be divided in two parts, 66 and 6931, that multiplied together give a triangular number (457446 = T₉₅₆).

The spelling of 666931 in words is "six hundred sixty-six thousand, nine hundred thirty-one".