81277813665 has 64 divisors (see below), whose sum is σ = 145884211200. Its totient is φ = 42932970432.

The previous prime is 81277813663. The next prime is 81277813691. The reversal of 81277813665 is 56631877218.

It is a happy number.

81277813665 is a `hidden beast` number, since 8 + 1 + 277 + 8 + 1 + 366 + 5 = 666.

It is not a de Polignac number, because 81277813665 - 2¹ = 81277813663 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81277813663) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 6373866 + ... + 6386604.

It is an arithmetic number, because the mean of its divisors is an integer number (2279440800).

Almost surely, 2^81277813665 is an apocalyptic number.

It is an amenable number.

81277813665 is a deficient number, since it is larger than the sum of its proper divisors (64606397535).

81277813665 is a wasteful number, since it uses less digits than its factorization.

81277813665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13203 (or 13197 counting only the distinct ones).

The product of its digits is 3386880, while the sum is 54.

The spelling of 81277813665 in words is "eighty-one billion, two hundred seventy-seven million, eight hundred thirteen thousand, six hundred sixty-five".