670661 has 4 divisors (see below), whose sum is σ = 672300. Its totient is φ = 669024.

The previous prime is 670639. The next prime is 670669. The reversal of 670661 is 166076.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 498436 + 172225 = 706^2 + 415^2 .

It is a cyclic number.

It is not a de Polignac number, because 670661 - 2⁶ = 670597 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 670661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (670669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 395 + ... + 1223.

It is an arithmetic number, because the mean of its divisors is an integer number (168075).

2⁶⁷⁰⁶⁶¹ is an apocalyptic number.

It is an amenable number.

670661 is a deficient number, since it is larger than the sum of its proper divisors (1639).

670661 is an equidigital number, since it uses as much as digits as its factorization.

670661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1638.

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 670661 is about 818.9389476634. The cubic root of 670661 is about 87.5321677645.

It can be divided in two parts, 670 and 661, that added together give a palindrome (1331).

The spelling of 670661 in words is "six hundred seventy thousand, six hundred sixty-one".