81319536 has 120 divisors (see below), whose sum is σ = 243424896. Its totient is φ = 25280640.

The previous prime is 81319531. The next prime is 81319577. The reversal of 81319536 is 63591318.

It is a happy number.

It is a super-2 number, since 2×81319536² = 13225733870510592, which contains 22 as substring.

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

It is a self number, because there is not a number n which added to its sum of digits gives 81319536.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81319531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 142131 + ... + 142701.

Almost surely, 2^81319536 is an apocalyptic number.

81319536 is a gapful number since it is divisible by the number (86) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81319536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121712448).

81319536 is an abundant number, since it is smaller than the sum of its proper divisors (162105360).

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

81319536 is a wasteful number, since it uses less digits than its factorization.

81319536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 651 (or 642 counting only the distinct ones).

The product of its digits is 19440, while the sum is 36.

The square root of 81319536 is about 9017.7345270306. The cubic root of 81319536 is about 433.2430760080.

The spelling of 81319536 in words is "eighty-one million, three hundred nineteen thousand, five hundred thirty-six".