667640 has 16 divisors (see below), whose sum is σ = 1502280. Its totient is φ = 267040.

The previous prime is 667631. The next prime is 667643. The reversal of 667640 is 46766.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667643) by changing a digit.

667640 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8306 + ... + 8385.

2⁶⁶⁷⁶⁴⁰ is an apocalyptic number.

It is an amenable number.

667640 is an abundant number, since it is smaller than the sum of its proper divisors (834640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

667640 is a wasteful number, since it uses less digits than its factorization.

667640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16702 (or 16698 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 29.

The square root of 667640 is about 817.0924060350. The cubic root of 667640 is about 87.4005400494.

The spelling of 667640 in words is "six hundred sixty-seven thousand, six hundred forty".