81387936 has 96 divisors (see below), whose sum is σ = 271313280. Its totient is φ = 23251968.

The previous prime is 81387931. The next prime is 81387937. The reversal of 81387936 is 63978318.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (96).

It is a super-2 number, since 2×81387936² = 13247992252680192, which contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 81387891 and 81387900.

It is not an unprimeable number, because it can be changed into a prime (81387931) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 681 + ... + 12776.

It is an arithmetic number, because the mean of its divisors is an integer number (2826180).

Almost surely, 2^81387936 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 81387936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (135656640).

81387936 is an abundant number, since it is smaller than the sum of its proper divisors (189925344).

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

81387936 is a wasteful number, since it uses less digits than its factorization.

81387936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13483 (or 13469 counting only the distinct ones).

The product of its digits is 217728, while the sum is 45.

The square root of 81387936 is about 9021.5262566818. The cubic root of 81387936 is about 433.3645126809.

The spelling of 81387936 in words is "eighty-one million, three hundred eighty-seven thousand, nine hundred thirty-six".