81917116164 has 144 divisors (see below), whose sum is σ = 236275183872. Its totient is φ = 23706418176.

The previous prime is 81917116153. The next prime is 81917116187. The reversal of 81917116164 is 46161171918.

81917116164 is a `hidden beast` number, since 8 + 1 + 9 + 17 + 11 + 616 + 4 = 666.

It is a super-4 number, since 4×81917116164⁴ (a number of 45 digits) contains 4444 as substring. Note that it is a super-d number also for d = 3.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 16569877 + ... + 16574819.

It is an arithmetic number, because the mean of its divisors is an integer number (1640799888).

Almost surely, 2^81917116164 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81917116164, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118137591936).

81917116164 is an abundant number, since it is smaller than the sum of its proper divisors (154358067708).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81917116164 is a wasteful number, since it uses less digits than its factorization.

81917116164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7066 (or 7061 counting only the distinct ones).

The product of its digits is 72576, while the sum is 45.

The spelling of 81917116164 in words is "eighty-one billion, nine hundred seventeen million, one hundred sixteen thousand, one hundred sixty-four".