243055991 has 2 divisors, whose sum is σ = 243055992. Its totient is φ = 243055990.

The previous prime is 243055963. The next prime is 243055993. The reversal of 243055991 is 199550342.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 243055991 - 2²² = 238861687 is a prime.

Together with 243055993, 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 (243055993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121527995 + 121527996.

It is an arithmetic number, because the mean of its divisors is an integer number (121527996).

Almost surely, 2^243055991 is an apocalyptic number.

243055991 is a deficient number, since it is larger than the sum of its proper divisors (1).

243055991 is an equidigital number, since it uses as much as digits as its factorization.

243055991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48600, while the sum is 38.

The square root of 243055991 is about 15590.2530768426. The cubic root of 243055991 is about 624.0730716190.

The spelling of 243055991 in words is "two hundred forty-three million, fifty-five thousand, nine hundred ninety-one".