81383636 has 6 divisors (see below), whose sum is σ = 142421370. Its totient is φ = 40691816.

The previous prime is 81383611. The next prime is 81383639. The reversal of 81383636 is 63638318.

It can be written as a sum of positive squares in only one way, i.e., 73788100 + 7595536 = 8590^2 + 2756^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81383636.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81383639) 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 as a sum of consecutive naturals, namely, 10172951 + ... + 10172958.

It is an arithmetic number, because the mean of its divisors is an integer number (23736895).

Almost surely, 2^81383636 is an apocalyptic number.

It is an amenable number.

81383636 is a deficient number, since it is larger than the sum of its proper divisors (61037734).

81383636 is a wasteful number, since it uses less digits than its factorization.

81383636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20345913 (or 20345911 counting only the distinct ones).

The product of its digits is 62208, while the sum is 38.

The square root of 81383636 is about 9021.2879346577. The cubic root of 81383636 is about 433.3568805087.

The spelling of 81383636 in words is "eighty-one million, three hundred eighty-three thousand, six hundred thirty-six".