249681 has 4 divisors (see below), whose sum is σ = 332912. Its totient is φ = 166452.

The previous prime is 249677. The next prime is 249703. The reversal of 249681 is 186942.

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 not a de Polignac number, because 249681 - 2² = 249677 is a prime.

It is a super-2 number, since 2×249681² = 124681203522, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 249681.

It is not an unprimeable number, because it can be changed into a prime (249671) 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, 41611 + ... + 41616.

It is an arithmetic number, because the mean of its divisors is an integer number (83228).

2²⁴⁹⁶⁸¹ is an apocalyptic number.

It is an amenable number.

249681 is a deficient number, since it is larger than the sum of its proper divisors (83231).

249681 is an equidigital number, since it uses as much as digits as its factorization.

249681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83230.

The product of its digits is 3456, while the sum is 30.

The square root of 249681 is about 499.6808981740. The cubic root of 249681 is about 62.9692467691.

The spelling of 249681 in words is "two hundred forty-nine thousand, six hundred eighty-one".