188644135681 has 4 divisors (see below), whose sum is σ = 188817682432. Its totient is φ = 188470588932.

The previous prime is 188644135657. The next prime is 188644135703. The reversal of 188644135681 is 186531446881.

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, and also an emirpimes, since its reverse is a distinct semiprime: 186531446881 = 13 ⋅14348572837.

It is a cyclic number.

It is not a de Polignac number, because 188644135681 - 2¹³ = 188644127489 is a prime.

It is a super-2 number, since 2×188644135681² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (188644135081) 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, 86771745 + ... + 86773918.

It is an arithmetic number, because the mean of its divisors is an integer number (47204420608).

Almost surely, 2^188644135681 is an apocalyptic number.

It is an amenable number.

188644135681 is a deficient number, since it is larger than the sum of its proper divisors (173546751).

188644135681 is a wasteful number, since it uses less digits than its factorization.

188644135681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173546750.

The product of its digits is 4423680, while the sum is 55.

The spelling of 188644135681 in words is "one hundred eighty-eight billion, six hundred forty-four million, one hundred thirty-five thousand, six hundred eighty-one".