81138648 has 16 divisors (see below), whose sum is σ = 202846680. Its totient is φ = 27046208.

The previous prime is 81138623. The next prime is 81138679. The reversal of 81138648 is 84683118.

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

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 1690365 + ... + 1690412.

Almost surely, 2^81138648 is an apocalyptic number.

It is an amenable number.

81138648 is an abundant number, since it is smaller than the sum of its proper divisors (121708032).

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

81138648 is a wasteful number, since it uses less digits than its factorization.

81138648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3380786 (or 3380782 counting only the distinct ones).

The product of its digits is 36864, while the sum is 39.

The square root of 81138648 is about 9007.6993733139. The cubic root of 81138648 is about 432.9216007628.

It can be divided in two parts, 8113 and 8648, that added together give a palindrome (16761).

The spelling of 81138648 in words is "eighty-one million, one hundred thirty-eight thousand, six hundred forty-eight".