43123235521 has 4 divisors (see below), whose sum is σ = 45659896452. Its totient is φ = 40586574592.

The previous prime is 43123235497. The next prime is 43123235557. The reversal of 43123235521 is 12553232134.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12553232134 = 2 ⋅6276616067.

It can be written as a sum of positive squares in 2 ways, for example, as 13216721296 + 29906514225 = 114964^2 + 172935^2 .

It is a cyclic number.

It is not a de Polignac number, because 43123235521 - 2²³ = 43114846913 is a prime.

It is a super-2 number, since 2×43123235521² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (43123235321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1268330440 + ... + 1268330473.

It is an arithmetic number, because the mean of its divisors is an integer number (11414974113).

Almost surely, 2^43123235521 is an apocalyptic number.

It is an amenable number.

43123235521 is a deficient number, since it is larger than the sum of its proper divisors (2536660931).

43123235521 is a wasteful number, since it uses less digits than its factorization.

43123235521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2536660930.

The product of its digits is 21600, while the sum is 31.

Adding to 43123235521 its reverse (12553232134), we get a palindrome (55676467655).

The spelling of 43123235521 in words is "forty-three billion, one hundred twenty-three million, two hundred thirty-five thousand, five hundred twenty-one".