243989 has 2 divisors, whose sum is σ = 243990. Its totient is φ = 243988.

The previous prime is 243973. The next prime is 244003. The reversal of 243989 is 989342.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 209764 + 34225 = 458^2 + 185^2 .

It is a cyclic number.

It is not a de Polignac number, because 243989 - 2⁴ = 243973 is a prime.

It is a Sophie Germain prime.

It is an Ulam number.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243589) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121994 + 121995.

It is an arithmetic number, because the mean of its divisors is an integer number (121995).

2²⁴³⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

243989 is a deficient number, since it is larger than the sum of its proper divisors (1).

243989 is an equidigital number, since it uses as much as digits as its factorization.

243989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 35.

The square root of 243989 is about 493.9524268591. The cubic root of 243989 is about 62.4870586539.

It can be divided in two parts, 2 and 43989, that multiplied together give a palindrome (87978).

The spelling of 243989 in words is "two hundred forty-three thousand, nine hundred eighty-nine".