243640399 has 2 divisors, whose sum is σ = 243640400. Its totient is φ = 243640398.

The previous prime is 243640367. The next prime is 243640427. The reversal of 243640399 is 993046342.

243640399 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 243640399 - 2⁵ = 243640367 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243640349) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121820199 + 121820200.

It is an arithmetic number, because the mean of its divisors is an integer number (121820200).

Almost surely, 2^243640399 is an apocalyptic number.

243640399 is a deficient number, since it is larger than the sum of its proper divisors (1).

243640399 is an equidigital number, since it uses as much as digits as its factorization.

243640399 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 139968, while the sum is 40.

The square root of 243640399 is about 15608.9845601820. The cubic root of 243640399 is about 624.5728486132.

The spelling of 243640399 in words is "two hundred forty-three million, six hundred forty thousand, three hundred ninety-nine".