666658 has 8 divisors (see below), whose sum is σ = 1004652. Its totient is φ = 331776.

The previous prime is 666649. The next prime is 666667. The reversal of 666658 is 856666.

It is an interprime number because it is at equal distance from previous prime (666649) and next prime (666667).

It can be written as a sum of positive squares in 2 ways, for example, as 393129 + 273529 = 627^2 + 523^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135 + ... + 1162.

2⁶⁶⁶⁶⁵⁸ is an apocalyptic number.

666658 is a deficient number, since it is larger than the sum of its proper divisors (337994).

666658 is a wasteful number, since it uses less digits than its factorization.

666658 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1556.

The product of its digits is 51840, while the sum is 37.

The square root of 666658 is about 816.4912736827. The cubic root of 666658 is about 87.3576679205.

It can be divided in two parts, 6666 and 58, that added together give a square (6724 = 82²).

The spelling of 666658 in words is "six hundred sixty-six thousand, six hundred fifty-eight".