243732721 has 2 divisors, whose sum is σ = 243732722. Its totient is φ = 243732720.

The previous prime is 243732691. The next prime is 243732763. The reversal of 243732721 is 127237342.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 181953121 + 61779600 = 13489^2 + 7860^2 .

It is a cyclic number.

It is not a de Polignac number, because 243732721 - 2²³ = 235344113 is a prime.

It is not a weakly prime, because it can be changed into another prime (243732821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121866360 + 121866361.

It is an arithmetic number, because the mean of its divisors is an integer number (121866361).

Almost surely, 2^243732721 is an apocalyptic number.

It is an amenable number.

243732721 is a deficient number, since it is larger than the sum of its proper divisors (1).

243732721 is an equidigital number, since it uses as much as digits as its factorization.

243732721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14112, while the sum is 31.

The square root of 243732721 is about 15611.9416153149. The cubic root of 243732721 is about 624.6517278865.

The spelling of 243732721 in words is "two hundred forty-three million, seven hundred thirty-two thousand, seven hundred twenty-one".