21131306523 has 12 divisors (see below), whose sum is σ = 30561306048. Its totient is φ = 14069857200.

The previous prime is 21131306509. The next prime is 21131306531. The reversal of 21131306523 is 32560313112.

21131306523 is a `hidden beast` number, since 2 + 1 + 1 + 3 + 1 + 3 + 0 + 652 + 3 = 666.

It is not a de Polignac number, because 21131306523 - 2⁴ = 21131306507 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21131306563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1465803 + ... + 1480148.

It is an arithmetic number, because the mean of its divisors is an integer number (2546775504).

Almost surely, 2^21131306523 is an apocalyptic number.

21131306523 is a deficient number, since it is larger than the sum of its proper divisors (9429999525).

21131306523 is a wasteful number, since it uses less digits than its factorization.

21131306523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2946754 (or 2946751 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 27.

Adding to 21131306523 its reverse (32560313112), we get a palindrome (53691619635).

The spelling of 21131306523 in words is "twenty-one billion, one hundred thirty-one million, three hundred six thousand, five hundred twenty-three".