81951965166 has 8 divisors (see below), whose sum is σ = 163903930344. Its totient is φ = 27317321720.

The previous prime is 81951965159. The next prime is 81951965191. The reversal of 81951965166 is 66156915918.

It is a sphenic number, since it is the product of 3 distinct primes.

81951965166 is an admirable number.

It is a super-2 number, since 2×81951965166² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6829330425 + ... + 6829330436.

It is an arithmetic number, because the mean of its divisors is an integer number (20487991293).

Almost surely, 2^81951965166 is an apocalyptic number.

81951965166 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

81951965166 is a wasteful number, since it uses less digits than its factorization.

81951965166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13658660866.

The product of its digits is 3499200, while the sum is 57.

The spelling of 81951965166 in words is "eighty-one billion, nine hundred fifty-one million, nine hundred sixty-five thousand, one hundred sixty-six".