81643649127 has 16 divisors (see below), whose sum is σ = 110477514240. Its totient is φ = 53622459072.

The previous prime is 81643649123. The next prime is 81643649141. The reversal of 81643649127 is 72194634618.

It is a happy number.

It is not a de Polignac number, because 81643649127 - 2² = 81643649123 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81643649127.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81643649123) 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 15 ways as a sum of consecutive naturals, for example, 268593 + ... + 485210.

It is an arithmetic number, because the mean of its divisors is an integer number (6904844640).

Almost surely, 2^81643649127 is an apocalyptic number.

81643649127 is a deficient number, since it is larger than the sum of its proper divisors (28833865113).

81643649127 is a wasteful number, since it uses less digits than its factorization.

81643649127 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 754342.

The product of its digits is 1741824, while the sum is 51.

The spelling of 81643649127 in words is "eighty-one billion, six hundred forty-three million, six hundred forty-nine thousand, one hundred twenty-seven".