666731 has 4 divisors (see below), whose sum is σ = 718032. Its totient is φ = 615432.

The previous prime is 666727. The next prime is 666733. The reversal of 666731 is 137666.

It is a happy number.

666731 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 666731 - 2² = 666727 is a prime.

It is a super-2 number, since 2×666731² = 889060452722, 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 = 666694 and 666703.

It is not an unprimeable number, because it can be changed into a prime (666733) 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, 25631 + ... + 25656.

It is an arithmetic number, because the mean of its divisors is an integer number (179508).

2⁶⁶⁶⁷³¹ is an apocalyptic number.

666731 is a deficient number, since it is larger than the sum of its proper divisors (51301).

666731 is a wasteful number, since it uses less digits than its factorization.

666731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51300.

The product of its digits is 4536, while the sum is 29.

The square root of 666731 is about 816.5359759374. The cubic root of 666731 is about 87.3608564004.

The spelling of 666731 in words is "six hundred sixty-six thousand, seven hundred thirty-one".