11865172381 has 4 divisors (see below), whose sum is σ = 12089043612. Its totient is φ = 11641301152.

The previous prime is 11865172379. The next prime is 11865172393. The reversal of 11865172381 is 18327156811.

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 9615567481 + 2249604900 = 98059^2 + 47430^2 .

It is a cyclic number.

It is not a de Polignac number, because 11865172381 - 2¹ = 11865172379 is a prime.

It is a super-2 number, since 2×11865172381² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11865172481) 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, 111935536 + ... + 111935641.

It is an arithmetic number, because the mean of its divisors is an integer number (3022260903).

Almost surely, 2^11865172381 is an apocalyptic number.

It is an amenable number.

11865172381 is a deficient number, since it is larger than the sum of its proper divisors (223871231).

11865172381 is an equidigital number, since it uses as much as digits as its factorization.

11865172381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223871230.

The product of its digits is 80640, while the sum is 43.

The spelling of 11865172381 in words is "eleven billion, eight hundred sixty-five million, one hundred seventy-two thousand, three hundred eighty-one".