243209993 has 4 divisors (see below), whose sum is σ = 261918468. Its totient is φ = 224501520.

The previous prime is 243209983. The next prime is 243210001. The reversal of 243209993 is 399902342.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 100240144 + 142969849 = 10012^2 + 11957^2 .

It is a cyclic number.

It is not a de Polignac number, because 243209993 - 2⁶ = 243209929 is a prime.

It is a super-2 number, since 2×243209993² = 118302201390120098, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 243209993.

It is not an unprimeable number, because it can be changed into a prime (243209963) 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, 9354218 + ... + 9354243.

It is an arithmetic number, because the mean of its divisors is an integer number (65479617).

Almost surely, 2^243209993 is an apocalyptic number.

It is an amenable number.

243209993 is a deficient number, since it is larger than the sum of its proper divisors (18708475).

243209993 is a wasteful number, since it uses less digits than its factorization.

243209993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18708474.

The product of its (nonzero) digits is 104976, while the sum is 41.

The square root of 243209993 is about 15595.1913422055. The cubic root of 243209993 is about 624.2048494994.

The spelling of 243209993 in words is "two hundred forty-three million, two hundred nine thousand, nine hundred ninety-three".