81294920172 has 36 divisors (see below), whose sum is σ = 205505883856. Its totient is φ = 27096936480.

The previous prime is 81294920153. The next prime is 81294920297. The reversal of 81294920172 is 27102949218.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-4 number, since 4×81294920172⁴ (a number of 45 digits) contains 4444 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 871722 + ... + 960462.

Almost surely, 2^81294920172 is an apocalyptic number.

It is an amenable number.

81294920172 is an abundant number, since it is smaller than the sum of its proper divisors (124210963684).

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

81294920172 is a wasteful number, since it uses less digits than its factorization.

81294920172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114198 (or 114193 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 45.

The spelling of 81294920172 in words is "eighty-one billion, two hundred ninety-four million, nine hundred twenty thousand, one hundred seventy-two".