243203551 has 2 divisors, whose sum is σ = 243203552. Its totient is φ = 243203550.

The previous prime is 243203549. The next prime is 243203557. The reversal of 243203551 is 155302342.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 243203551 - 2¹ = 243203549 is a prime.

Together with 243203549, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243203557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121601775 + 121601776.

It is an arithmetic number, because the mean of its divisors is an integer number (121601776).

Almost surely, 2^243203551 is an apocalyptic number.

243203551 is a deficient number, since it is larger than the sum of its proper divisors (1).

243203551 is an equidigital number, since it uses as much as digits as its factorization.

243203551 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3600, while the sum is 25.

The square root of 243203551 is about 15594.9848028140. The cubic root of 243203551 is about 624.1993382632.

Adding to 243203551 its reverse (155302342), we get a palindrome (398505893).

The spelling of 243203551 in words is "two hundred forty-three million, two hundred three thousand, five hundred fifty-one".