243491557 has 2 divisors, whose sum is σ = 243491558. Its totient is φ = 243491556.

The previous prime is 243491551. The next prime is 243491581. The reversal of 243491557 is 755194342.

It is a happy number.

243491557 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 123676641 + 119814916 = 11121^2 + 10946^2 .

It is a cyclic number.

It is not a de Polignac number, because 243491557 - 2¹¹ = 243489509 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (243491551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121745778 + 121745779.

It is an arithmetic number, because the mean of its divisors is an integer number (121745779).

Almost surely, 2^243491557 is an apocalyptic number.

It is an amenable number.

243491557 is a deficient number, since it is larger than the sum of its proper divisors (1).

243491557 is an equidigital number, since it uses as much as digits as its factorization.

243491557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 151200, while the sum is 40.

The square root of 243491557 is about 15604.2160008121. The cubic root of 243491557 is about 624.4456370762.

The spelling of 243491557 in words is "two hundred forty-three million, four hundred ninety-one thousand, five hundred fifty-seven".