243721091 has 4 divisors (see below), whose sum is σ = 243752712. Its totient is φ = 243689472.

The previous prime is 243721043. The next prime is 243721099. The reversal of 243721091 is 190127342.

243721091 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 190127342 = 2 ⋅95063671.

It is a cyclic number.

It is not a de Polignac number, because 243721091 - 2¹⁸ = 243458947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (243721099) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4160 + ... + 22466.

It is an arithmetic number, because the mean of its divisors is an integer number (60938178).

Almost surely, 2^243721091 is an apocalyptic number.

243721091 is a deficient number, since it is larger than the sum of its proper divisors (31621).

243721091 is a wasteful number, since it uses less digits than its factorization.

243721091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31620.

The product of its (nonzero) digits is 3024, while the sum is 29.

The square root of 243721091 is about 15611.5691395836. The cubic root of 243721091 is about 624.6417923923.

The spelling of 243721091 in words is "two hundred forty-three million, seven hundred twenty-one thousand, ninety-one".