659681 has 4 divisors (see below), whose sum is σ = 719664. Its totient is φ = 599700.

The previous prime is 659671. The next prime is 659689. The reversal of 659681 is 186956.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-659681 is a prime.

It is a super-2 number, since 2×659681² = 870358043522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (659689) 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 3 ways as a sum of consecutive naturals, for example, 29975 + ... + 29996.

It is an arithmetic number, because the mean of its divisors is an integer number (179916).

2⁶⁵⁹⁶⁸¹ is an apocalyptic number.

It is an amenable number.

659681 is a deficient number, since it is larger than the sum of its proper divisors (59983).

659681 is a wasteful number, since it uses less digits than its factorization.

659681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59982.

The product of its digits is 12960, while the sum is 35.

The square root of 659681 is about 812.2074858064. The cubic root of 659681 is about 87.0518473710.

The spelling of 659681 in words is "six hundred fifty-nine thousand, six hundred eighty-one".