243251581 has 2 divisors, whose sum is σ = 243251582. Its totient is φ = 243251580.

The previous prime is 243251563. The next prime is 243251599. The reversal of 243251581 is 185152342.

It is a balanced prime because it is at equal distance from previous prime (243251563) and next prime (243251599).

It can be written as a sum of positive squares in only one way, i.e., 240529081 + 2722500 = 15509^2 + 1650^2 .

It is a cyclic number.

It is not a de Polignac number, because 243251581 - 2²¹ = 241154429 is a prime.

It is a super-2 number, since 2×243251581² = 118342663317999122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243251501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121625790 + 121625791.

It is an arithmetic number, because the mean of its divisors is an integer number (121625791).

Almost surely, 2^243251581 is an apocalyptic number.

It is an amenable number.

243251581 is a deficient number, since it is larger than the sum of its proper divisors (1).

243251581 is an equidigital number, since it uses as much as digits as its factorization.

243251581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9600, while the sum is 31.

The square root of 243251581 is about 15596.5246449329. The cubic root of 243251581 is about 624.2404263706.

The spelling of 243251581 in words is "two hundred forty-three million, two hundred fifty-one thousand, five hundred eighty-one".