243939881 has 2 divisors, whose sum is σ = 243939882. Its totient is φ = 243939880.

The previous prime is 243939869. The next prime is 243939887. The reversal of 243939881 is 188939342.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 151683856 + 92256025 = 12316^2 + 9605^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-243939881 is a prime.

It is a super-2 number, since 2×243939881² = 119013331084588322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (243939887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121969940 + 121969941.

It is an arithmetic number, because the mean of its divisors is an integer number (121969941).

Almost surely, 2^243939881 is an apocalyptic number.

It is an amenable number.

243939881 is a deficient number, since it is larger than the sum of its proper divisors (1).

243939881 is an equidigital number, since it uses as much as digits as its factorization.

243939881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 373248, while the sum is 47.

The square root of 243939881 is about 15618.5748709669. The cubic root of 243939881 is about 624.8286514811.

The spelling of 243939881 in words is "two hundred forty-three million, nine hundred thirty-nine thousand, eight hundred eighty-one".