243121209889 has 2 divisors, whose sum is σ = 243121209890. Its totient is φ = 243121209888.

The previous prime is 243121209883. The next prime is 243121209917. The reversal of 243121209889 is 988902121342.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 193789246225 + 49331963664 = 440215^2 + 222108^2 .

It is a cyclic number.

It is not a de Polignac number, because 243121209889 - 2⁵ = 243121209857 is a prime.

It is not a weakly prime, because it can be changed into another prime (243121209883) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121560604944 + 121560604945.

It is an arithmetic number, because the mean of its divisors is an integer number (121560604945).

Almost surely, 2^243121209889 is an apocalyptic number.

It is an amenable number.

243121209889 is a deficient number, since it is larger than the sum of its proper divisors (1).

243121209889 is an equidigital number, since it uses as much as digits as its factorization.

243121209889 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 497664, while the sum is 49.

The spelling of 243121209889 in words is "two hundred forty-three billion, one hundred twenty-one million, two hundred nine thousand, eight hundred eighty-nine".