81516384 has 72 divisors (see below), whose sum is σ = 244029240. Its totient is φ = 25740288.

The previous prime is 81516373. The next prime is 81516397. The reversal of 81516384 is 48361518.

81516384 is a `hidden beast` number, since 8 + 15 + 1 + 638 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-3 number, since 3×81516384³ (a number of 25 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1977 + ... + 12920.

It is an arithmetic number, because the mean of its divisors is an integer number (3389295).

Almost surely, 2^81516384 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 81516384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (122014620).

81516384 is an abundant number, since it is smaller than the sum of its proper divisors (162512856).

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

81516384 is a wasteful number, since it uses less digits than its factorization.

81516384 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14932 (or 14921 counting only the distinct ones).

The product of its digits is 23040, while the sum is 36.

The square root of 81516384 is about 9028.6424228673. The cubic root of 81516384 is about 433.5923742435.

It can be divided in two parts, 8151 and 6384, that added together give a triangular number (14535 = T₁₇₀).

The spelling of 81516384 in words is "eighty-one million, five hundred sixteen thousand, three hundred eighty-four".