660881 has 8 divisors (see below), whose sum is σ = 736680. Its totient is φ = 588672.

The previous prime is 660853. The next prime is 660887. The reversal of 660881 is 188066.

It can be written as a sum of positive squares in 4 ways, for example, as 6400 + 654481 = 80^2 + 809^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 660881 - 2⁶ = 660817 is a prime.

It is a super-2 number, since 2×660881² = 873527392322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (660887) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 500 + ... + 1253.

It is an arithmetic number, because the mean of its divisors is an integer number (92085).

2⁶⁶⁰⁸⁸¹ is an apocalyptic number.

It is an amenable number.

660881 is a deficient number, since it is larger than the sum of its proper divisors (75799).

660881 is a wasteful number, since it uses less digits than its factorization.

660881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1795.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 660881 is about 812.9458776573. The cubic root of 660881 is about 87.1045996052.

The spelling of 660881 in words is "six hundred sixty thousand, eight hundred eighty-one".