660581 has 4 divisors (see below), whose sum is σ = 663564. Its totient is φ = 657600.

The previous prime is 660563. The next prime is 660589. The reversal of 660581 is 185066.

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

It can be written as a sum of positive squares in 2 ways, for example, as 348100 + 312481 = 590^2 + 559^2 .

It is a cyclic number.

It is not a de Polignac number, because 660581 - 2¹⁴ = 644197 is a prime.

It is a super-2 number, since 2×660581² = 872734515122, which contains 22 as substring.

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 660581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660589) 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, 1130 + ... + 1611.

It is an arithmetic number, because the mean of its divisors is an integer number (165891).

2⁶⁶⁰⁵⁸¹ is an apocalyptic number.

It is an amenable number.

660581 is a deficient number, since it is larger than the sum of its proper divisors (2983).

660581 is a wasteful number, since it uses less digits than its factorization.

660581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2982.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 660581 is about 812.7613425846. The cubic root of 660581 is about 87.0914175371.

The spelling of 660581 in words is "six hundred sixty thousand, five hundred eighty-one".