1231817645181 has 4 divisors (see below), whose sum is σ = 1642423526912. Its totient is φ = 821211763452.

The previous prime is 1231817645173. The next prime is 1231817645189. The reversal of 1231817645181 is 1815467181321.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (1231817645173) and next prime (1231817645189).

It is not a de Polignac number, because 1231817645181 - 2³ = 1231817645173 is a prime.

It is a super-2 number, since 2×1231817645181² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1231817645181.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231817645189) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 205302940861 + ... + 205302940866.

It is an arithmetic number, because the mean of its divisors is an integer number (410605881728).

Almost surely, 2^{1231817645181} is an apocalyptic number.

It is an amenable number.

1231817645181 is a deficient number, since it is larger than the sum of its proper divisors (410605881731).

1231817645181 is an equidigital number, since it uses as much as digits as its factorization.

1231817645181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 410605881730.

The product of its digits is 322560, while the sum is 48.

The spelling of 1231817645181 in words is "one trillion, two hundred thirty-one billion, eight hundred seventeen million, six hundred forty-five thousand, one hundred eighty-one".