243155042021 has 4 divisors (see below), whose sum is σ = 249085652844. Its totient is φ = 237224431200.

The previous prime is 243155041973. The next prime is 243155042047. The reversal of 243155042021 is 120240551342.

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 86604249796 + 156550792225 = 294286^2 + 395665^2 .

It is a cyclic number.

It is not a de Polignac number, because 243155042021 - 2¹⁴ = 243155025637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243155042071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2965305350 + ... + 2965305431.

It is an arithmetic number, because the mean of its divisors is an integer number (62271413211).

Almost surely, 2^243155042021 is an apocalyptic number.

It is an amenable number.

243155042021 is a deficient number, since it is larger than the sum of its proper divisors (5930610823).

243155042021 is an equidigital number, since it uses as much as digits as its factorization.

243155042021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5930610822.

The product of its (nonzero) digits is 9600, while the sum is 29.

Adding to 243155042021 its reverse (120240551342), we get a palindrome (363395593363).

The spelling of 243155042021 in words is "two hundred forty-three billion, one hundred fifty-five million, forty-two thousand, twenty-one".