243791813 has 4 divisors (see below), whose sum is σ = 243823788. Its totient is φ = 243759840.

The previous prime is 243791809. The next prime is 243791837. The reversal of 243791813 is 318197342.

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: 318197342 = 2 ⋅159098671.

It can be written as a sum of positive squares in 2 ways, for example, as 241429444 + 2362369 = 15538^2 + 1537^2 .

It is a cyclic number.

It is not a de Polignac number, because 243791813 - 2² = 243791809 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243791803) 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, 2843 + ... + 22263.

It is an arithmetic number, because the mean of its divisors is an integer number (60955947).

Almost surely, 2^243791813 is an apocalyptic number.

It is an amenable number.

243791813 is a deficient number, since it is larger than the sum of its proper divisors (31975).

243791813 is a wasteful number, since it uses less digits than its factorization.

243791813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31974.

The product of its digits is 36288, while the sum is 38.

The square root of 243791813 is about 15613.8340262730. The cubic root of 243791813 is about 624.7022052251.

The spelling of 243791813 in words is "two hundred forty-three million, seven hundred ninety-one thousand, eight hundred thirteen".