243135212521 has 2 divisors, whose sum is σ = 243135212522. Its totient is φ = 243135212520.

The previous prime is 243135212503. The next prime is 243135212543. The reversal of 243135212521 is 125212531342.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 129481946896 + 113653265625 = 359836^2 + 337125^2 .

It is a cyclic number.

It is not a de Polignac number, because 243135212521 - 2¹⁵ = 243135179753 is a prime.

It is a super-2 number, since 2×243135212521² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (243135212921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121567606260 + 121567606261.

It is an arithmetic number, because the mean of its divisors is an integer number (121567606261).

Almost surely, 2^243135212521 is an apocalyptic number.

It is an amenable number.

243135212521 is a deficient number, since it is larger than the sum of its proper divisors (1).

243135212521 is an equidigital number, since it uses as much as digits as its factorization.

243135212521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14400, while the sum is 31.

Adding to 243135212521 its reverse (125212531342), we get a palindrome (368347743863).

The spelling of 243135212521 in words is "two hundred forty-three billion, one hundred thirty-five million, two hundred twelve thousand, five hundred twenty-one".