243740877025991 has 2 divisors, whose sum is σ = 243740877025992. Its totient is φ = 243740877025990.

The previous prime is 243740877025903. The next prime is 243740877025993. The reversal of 243740877025991 is 199520778047342.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 243740877025991 - 2³⁸ = 243465999119047 is a prime.

It is a Sophie Germain prime.

Together with 243740877025993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243740877025993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121870438512995 + 121870438512996.

It is an arithmetic number, because the mean of its divisors is an integer number (121870438512996).

Almost surely, 2^{243740877025991} is an apocalyptic number.

243740877025991 is a deficient number, since it is larger than the sum of its proper divisors (1).

243740877025991 is an equidigital number, since it uses as much as digits as its factorization.

243740877025991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 213373440, while the sum is 68.

The spelling of 243740877025991 in words is "two hundred forty-three trillion, seven hundred forty billion, eight hundred seventy-seven million, twenty-five thousand, nine hundred ninety-one".