81397836 has 108 divisors (see below), whose sum is σ = 236206152. Its totient is φ = 23542272.

The previous prime is 81397829. The next prime is 81397837. The reversal of 81397836 is 63879318.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 81397791 and 81397800.

It is not an unprimeable number, because it can be changed into a prime (81397837) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 103035 + ... + 103821.

It is an arithmetic number, because the mean of its divisors is an integer number (2187094).

Almost surely, 2^81397836 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 81397836, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118103076).

81397836 is an abundant number, since it is smaller than the sum of its proper divisors (154808316).

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

81397836 is a wasteful number, since it uses less digits than its factorization.

81397836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 840 (or 822 counting only the distinct ones).

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

The square root of 81397836 is about 9022.0749276428. The cubic root of 81397836 is about 433.3820834043.

The spelling of 81397836 in words is "eighty-one million, three hundred ninety-seven thousand, eight hundred thirty-six".