671666 has 4 divisors (see below), whose sum is σ = 1007502. Its totient is φ = 335832.

The previous prime is 671651. The next prime is 671681. The reversal of 671666 is 666176.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (671651) and next prime (671681).

It can be written as a sum of positive squares in only one way, i.e., 442225 + 229441 = 665^2 + 479^2 .

It is a super-2 number, since 2×671666² = 902270431112, which contains 22 as substring.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 671666.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 167915 + ... + 167918.

2⁶⁷¹⁶⁶⁶ is an apocalyptic number.

671666 is a deficient number, since it is larger than the sum of its proper divisors (335836).

671666 is a wasteful number, since it uses less digits than its factorization.

671666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 335835.

The product of its digits is 9072, while the sum is 32.

The square root of 671666 is about 819.5523168169. The cubic root of 671666 is about 87.5758688910.

The spelling of 671666 in words is "six hundred seventy-one thousand, six hundred sixty-six".