659981 has 6 divisors (see below), whose sum is σ = 767790. Its totient is φ = 565656.

The previous prime is 659963. The next prime is 659983. The reversal of 659981 is 189956.

It can be written as a sum of positive squares in only one way, i.e., 592900 + 67081 = 770^2 + 259^2 .

It is not a de Polignac number, because 659981 - 2⁶ = 659917 is a prime.

It is a super-2 number, since 2×659981² = 871149840722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (659983) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 6686 + ... + 6783.

It is an arithmetic number, because the mean of its divisors is an integer number (127965).

2⁶⁵⁹⁹⁸¹ is an apocalyptic number.

It is an amenable number.

659981 is a deficient number, since it is larger than the sum of its proper divisors (107809).

659981 is a wasteful number, since it uses less digits than its factorization.

659981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13483 (or 13476 counting only the distinct ones).

The product of its digits is 19440, while the sum is 38.

The square root of 659981 is about 812.3921466878. The cubic root of 659981 is about 87.0650414231.

The spelling of 659981 in words is "six hundred fifty-nine thousand, nine hundred eighty-one".