11531387531 has 4 divisors (see below), whose sum is σ = 11531619792. Its totient is φ = 11531155272.

The previous prime is 11531387503. The next prime is 11531387563. The reversal of 11531387531 is 13578313511.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 11531387531 - 2¹⁰ = 11531386507 is a prime.

It is a super-2 number, since 2×11531387531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11531387591) 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, 8255 + ... + 152088.

It is an arithmetic number, because the mean of its divisors is an integer number (2882904948).

Almost surely, 2^11531387531 is an apocalyptic number.

11531387531 is a deficient number, since it is larger than the sum of its proper divisors (232261).

11531387531 is an equidigital number, since it uses as much as digits as its factorization.

11531387531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 232260.

The product of its digits is 37800, while the sum is 38.

The spelling of 11531387531 in words is "eleven billion, five hundred thirty-one million, three hundred eighty-seven thousand, five hundred thirty-one".