243121320 has 96 divisors (see below), whose sum is σ = 850941000. Its totient is φ = 59844096.

The previous prime is 243121309. The next prime is 243121327. The reversal of 243121320 is 23121342.

243121320 is a `hidden beast` number, since 2 + 431 + 213 + 20 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 115476516 + 127644804 = 10746^2 + 11298^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 243121293 and 243121302.

It is not an unprimeable number, because it can be changed into a prime (243121327) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21295 + ... + 30654.

Almost surely, 2^243121320 is an apocalyptic number.

243121320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

243121320 is an abundant number, since it is smaller than the sum of its proper divisors (607819680).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

243121320 is a wasteful number, since it uses less digits than its factorization.

243121320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51979 (or 51972 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 243121320 is about 15592.3481233585. The cubic root of 243121320 is about 624.1289797485.

Adding to 243121320 its reverse (23121342), we get a palindrome (266242662).

The spelling of 243121320 in words is "two hundred forty-three million, one hundred twenty-one thousand, three hundred twenty".