81317392 has 120 divisors (see below), whose sum is σ = 189932040. Its totient is φ = 33546240.

The previous prime is 81317389. The next prime is 81317393. The reversal of 81317392 is 29371318.

It can be written as a sum of positive squares in 12 ways, for example, as 51897616 + 29419776 = 7204^2 + 5424^2 .

It is a super-2 number, since 2×81317392² = 13225036483363328, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is not an unprimeable number, because it can be changed into a prime (81317393) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 1333042 + ... + 1333102.

It is an arithmetic number, because the mean of its divisors is an integer number (1582767).

Almost surely, 2^81317392 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 81317392, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (94966020).

81317392 is an abundant number, since it is smaller than the sum of its proper divisors (108614648).

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

81317392 is a wasteful number, since it uses less digits than its factorization.

81317392 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141 (or 122 counting only the distinct ones).

The product of its digits is 9072, while the sum is 34.

The square root of 81317392 is about 9017.6156493832. The cubic root of 81317392 is about 433.2392684714.

The spelling of 81317392 in words is "eighty-one million, three hundred seventeen thousand, three hundred ninety-two".