81368136 has 96 divisors (see below), whose sum is σ = 227012760. Its totient is φ = 26320896.

The previous prime is 81368129. The next prime is 81368167. The reversal of 81368136 is 63186318.

It can be written as a sum of positive squares in 4 ways, for example, as 52272900 + 29095236 = 7230^2 + 5394^2 .

It is a super-2 number, since 2×81368136² = 13241547112228992, which contains 22 as substring.

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

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 81368136.

It is a congruent number.

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 23 ways as a sum of consecutive naturals, for example, 593860 + ... + 593996.

Almost surely, 2^81368136 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 81368136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (113506380).

81368136 is an abundant number, since it is smaller than the sum of its proper divisors (145644624).

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

81368136 is a wasteful number, since it uses less digits than its factorization.

81368136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 335 (or 328 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 81368136 is about 9020.4288146407. The cubic root of 81368136 is about 433.3293669591.

The spelling of 81368136 in words is "eighty-one million, three hundred sixty-eight thousand, one hundred thirty-six".