243400551 has 4 divisors (see below), whose sum is σ = 324534072. Its totient is φ = 162267032.

The previous prime is 243400529. The next prime is 243400579. The reversal of 243400551 is 155004342.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 243400551 - 2¹⁷ = 243269479 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243400151) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40566756 + ... + 40566761.

It is an arithmetic number, because the mean of its divisors is an integer number (81133518).

Almost surely, 2^243400551 is an apocalyptic number.

243400551 is a deficient number, since it is larger than the sum of its proper divisors (81133521).

243400551 is an equidigital number, since it uses as much as digits as its factorization.

243400551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81133520.

The product of its (nonzero) digits is 2400, while the sum is 24.

The square root of 243400551 is about 15601.2996574003. The cubic root of 243400551 is about 624.3678309820.

Adding to 243400551 its reverse (155004342), we get a palindrome (398404893).

It can be divided in two parts, 243400 and 551, that added together give a triangular number (243951 = T₆₉₈).

The spelling of 243400551 in words is "two hundred forty-three million, four hundred thousand, five hundred fifty-one".