243121021533 has 48 divisors (see below), whose sum is σ = 401761179456. Its totient is φ = 145963762560.

The previous prime is 243121021513. The next prime is 243121021543. The reversal of 243121021533 is 335120121342.

243121021533 is a `hidden beast` number, since 2 + 4 + 3 + 121 + 0 + 2 + 1 + 533 = 666.

It is not a de Polignac number, because 243121021533 - 2¹⁰ = 243121020509 is a prime.

It is a super-2 number, since 2×243121021533² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 243121021497 and 243121021506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243121021513) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 809035 + ... + 1068072.

It is an arithmetic number, because the mean of its divisors is an integer number (8370024572).

Almost surely, 2^243121021533 is an apocalyptic number.

It is an amenable number.

243121021533 is a deficient number, since it is larger than the sum of its proper divisors (158640157923).

243121021533 is a wasteful number, since it uses less digits than its factorization.

243121021533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1877176 (or 1877164 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

Adding to 243121021533 its reverse (335120121342), we get a palindrome (578241142875).

The spelling of 243121021533 in words is "two hundred forty-three billion, one hundred twenty-one million, twenty-one thousand, five hundred thirty-three".