249921 has 12 divisors (see below), whose sum is σ = 412672. Its totient is φ = 142776.

The previous prime is 249911. The next prime is 249923. The reversal of 249921 is 129942.

It is not a de Polignac number, because 249921 - 2⁶ = 249857 is a prime.

It is a Duffinian number.

249921 is a lucky number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 249921.

It is not an unprimeable number, because it can be changed into a prime (249923) 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 11 ways as a sum of consecutive naturals, for example, 1921 + ... + 2046.

2²⁴⁹⁹²¹ is an apocalyptic number.

249921 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

249921 is a deficient number, since it is larger than the sum of its proper divisors (162751).

249921 is a wasteful number, since it uses less digits than its factorization.

249921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3980 (or 3977 counting only the distinct ones).

The product of its digits is 1296, while the sum is 27.

The square root of 249921 is about 499.9209937580. The cubic root of 249921 is about 62.9894162115.

The spelling of 249921 in words is "two hundred forty-nine thousand, nine hundred twenty-one".