518681 has 4 divisors (see below), whose sum is σ = 546000. Its totient is φ = 491364.

The previous prime is 518657. The next prime is 518689. The reversal of 518681 is 186815.

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, and also an emirpimes, since its reverse is a distinct semiprime: 186815 = 5 ⋅37363.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-518681 is a prime.

It is a super-2 number, since 2×518681² = 538059959522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (518689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13631 + ... + 13668.

It is an arithmetic number, because the mean of its divisors is an integer number (136500).

2⁵¹⁸⁶⁸¹ is an apocalyptic number.

It is an amenable number.

518681 is a deficient number, since it is larger than the sum of its proper divisors (27319).

518681 is a wasteful number, since it uses less digits than its factorization.

518681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27318.

The product of its digits is 1920, while the sum is 29.

The square root of 518681 is about 720.1951124522. The cubic root of 518681 is about 80.3464660994.

The spelling of 518681 in words is "five hundred eighteen thousand, six hundred eighty-one".