81117473661 has 96 divisors (see below), whose sum is σ = 144985917440. Its totient is φ = 42661406592.

The previous prime is 81117473651. The next prime is 81117473681. The reversal of 81117473661 is 16637471118.

It is a happy number.

81117473661 is a `hidden beast` number, since 8 + 1 + 117 + 473 + 6 + 61 = 666.

It is not a de Polignac number, because 81117473661 - 2⁷ = 81117473533 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81117473611) 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 95 ways as a sum of consecutive naturals, for example, 47078346 + ... + 47080068.

Almost surely, 2^81117473661 is an apocalyptic number.

It is an amenable number.

81117473661 is a deficient number, since it is larger than the sum of its proper divisors (63868443779).

81117473661 is a wasteful number, since it uses less digits than its factorization.

81117473661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2855 (or 2852 counting only the distinct ones).

The product of its digits is 169344, while the sum is 45.

The spelling of 81117473661 in words is "eighty-one billion, one hundred seventeen million, four hundred seventy-three thousand, six hundred sixty-one".