231355136521 has 4 divisors (see below), whose sum is σ = 231583523652. Its totient is φ = 231126749392.

The previous prime is 231355136501. The next prime is 231355136539. The reversal of 231355136521 is 125631553132.

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 66389190921 + 164965945600 = 257661^2 + 406160^2 .

It is a cyclic number.

It is not a de Polignac number, because 231355136521 - 2²¹ = 231353039369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (231355136501) 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, 114192046 + ... + 114194071.

It is an arithmetic number, because the mean of its divisors is an integer number (57895880913).

Almost surely, 2^231355136521 is an apocalyptic number.

It is an amenable number.

231355136521 is a deficient number, since it is larger than the sum of its proper divisors (228387131).

231355136521 is a wasteful number, since it uses less digits than its factorization.

231355136521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228387130.

The product of its digits is 81000, while the sum is 37.

Adding to 231355136521 its reverse (125631553132), we get a palindrome (356986689653).

The spelling of 231355136521 in words is "two hundred thirty-one billion, three hundred fifty-five million, one hundred thirty-six thousand, five hundred twenty-one".