243876721 has 32 divisors (see below), whose sum is σ = 284046336. Its totient is φ = 207360000.

The previous prime is 243876707. The next prime is 243876727. The reversal of 243876721 is 127678342.

It is a 4-Lehmer number, since φ(243876721) divides (243876721-1)⁴.

It is a cyclic number.

It is not a de Polignac number, because 243876721 - 2⁷ = 243876593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (243876727) 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 in 31 ways as a sum of consecutive naturals, for example, 2414571 + ... + 2414671.

It is an arithmetic number, because the mean of its divisors is an integer number (8876448).

Almost surely, 2^243876721 is an apocalyptic number.

It is an amenable number.

243876721 is a deficient number, since it is larger than the sum of its proper divisors (40169615).

243876721 is a wasteful number, since it uses less digits than its factorization.

243876721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 313.

The product of its digits is 112896, while the sum is 40.

The square root of 243876721 is about 15616.5527886278. The cubic root of 243876721 is about 624.7747207286.

The spelling of 243876721 in words is "two hundred forty-three million, eight hundred seventy-six thousand, seven hundred twenty-one".