81455138172 has 144 divisors (see below), whose sum is σ = 226720166400. Its totient is φ = 24543160320.

The previous prime is 81455138123. The next prime is 81455138173. The reversal of 81455138172 is 27183155418.

81455138172 is a `hidden beast` number, since 8 + 14 + 551 + 3 + 81 + 7 + 2 = 666.

It is a super-2 number, since 2×81455138172² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81455138173) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3377854 + ... + 3401882.

It is an arithmetic number, because the mean of its divisors is an integer number (1574445600).

Almost surely, 2^81455138172 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 81455138172, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (113360083200).

81455138172 is an abundant number, since it is smaller than the sum of its proper divisors (145265028228).

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

81455138172 is a wasteful number, since it uses less digits than its factorization.

81455138172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24276 (or 24271 counting only the distinct ones).

The product of its digits is 268800, while the sum is 45.

The spelling of 81455138172 in words is "eighty-one billion, four hundred fifty-five million, one hundred thirty-eight thousand, one hundred seventy-two".