81243648 has 120 divisors (see below), whose sum is σ = 243531288. Its totient is φ = 27039744.

The previous prime is 81243607. The next prime is 81243661. The reversal of 81243648 is 84634218.

81243648 is a `hidden beast` number, since 8 + 1 + 2 + 4 + 3 + 648 = 666.

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 congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 124090 + ... + 124742.

Almost surely, 2^81243648 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 81243648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121765644).

81243648 is an abundant number, since it is smaller than the sum of its proper divisors (162287640).

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

81243648 is an frugal number, since it uses more digits than its factorization.

81243648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 686 (or 658 counting only the distinct ones).

The product of its digits is 36864, while the sum is 36.

The square root of 81243648 is about 9013.5258362086. The cubic root of 81243648 is about 433.1082655029.

The spelling of 81243648 in words is "eighty-one million, two hundred forty-three thousand, six hundred forty-eight".