81693312 has 64 divisors (see below), whose sum is σ = 228439200. Its totient is φ = 25795584.

The previous prime is 81693289. The next prime is 81693371. The reversal of 81693312 is 21339618.

It is a tau number, because it is divible by the number of its divisors (64).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1698 + ... + 12894.

Almost surely, 2^81693312 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 81693312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (114219600).

81693312 is an abundant number, since it is smaller than the sum of its proper divisors (146745888).

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

81693312 is a wasteful number, since it uses less digits than its factorization.

81693312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11233 (or 11221 counting only the distinct ones).

The product of its digits is 7776, while the sum is 33.

The square root of 81693312 is about 9038.4352628096. The cubic root of 81693312 is about 433.9058457718.

The spelling of 81693312 in words is "eighty-one million, six hundred ninety-three thousand, three hundred twelve".