243991225 has 24 divisors (see below), whose sum is σ = 322579800. Its totient is φ = 182430720.

The previous prime is 243991207. The next prime is 243991243. The reversal of 243991225 is 522199342.

It is an interprime number because it is at equal distance from previous prime (243991207) and next prime (243991243).

It can be written as a sum of positive squares in 12 ways, for example, as 16192576 + 227798649 = 4024^2 + 15093^2 .

It is not a de Polignac number, because 243991225 - 2⁵ = 243991193 is a prime.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 61399 + ... + 65251.

It is an arithmetic number, because the mean of its divisors is an integer number (13440825).

Almost surely, 2^243991225 is an apocalyptic number.

243991225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

243991225 is a deficient number, since it is larger than the sum of its proper divisors (78588575).

243991225 is a wasteful number, since it uses less digits than its factorization.

243991225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4029 (or 4024 counting only the distinct ones).

The product of its digits is 38880, while the sum is 37.

The square root of 243991225 is about 15620.2184683826. The cubic root of 243991225 is about 624.8724859861.

The spelling of 243991225 in words is "two hundred forty-three million, nine hundred ninety-one thousand, two hundred twenty-five".