243121021506 has 32 divisors (see below), whose sum is σ = 589384296000. Its totient is φ = 73673036640.

The previous prime is 243121021489. The next prime is 243121021513. The reversal of 243121021506 is 605120121342.

243121021506 is a `hidden beast` number, since 2 + 43 + 12 + 102 + 1 + 506 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 243121021506.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 204646731 + ... + 204647918.

It is an arithmetic number, because the mean of its divisors is an integer number (18418259250).

Almost surely, 2^243121021506 is an apocalyptic number.

243121021506 is an abundant number, since it is smaller than the sum of its proper divisors (346263274494).

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

243121021506 is a wasteful number, since it uses less digits than its factorization.

243121021506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 409294671 (or 409294665 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

Adding to 243121021506 its reverse (605120121342), we get a palindrome (848241142848).

The spelling of 243121021506 in words is "two hundred forty-three billion, one hundred twenty-one million, twenty-one thousand, five hundred six".