81144648 has 48 divisors (see below), whose sum is σ = 236674620. Its totient is φ = 24967296.

The previous prime is 81144641. The next prime is 81144677. The reversal of 81144648 is 84644118.

81144648 is a `hidden beast` number, since 8 + 1 + 1 + 4 + 4 + 648 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 79602084 + 1542564 = 8922^2 + 1242^2 .

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 not an unprimeable number, because it can be changed into a prime (81144641) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 42411 + ... + 44282.

Almost surely, 2^81144648 is an apocalyptic number.

It is an amenable number.

81144648 is an abundant number, since it is smaller than the sum of its proper divisors (155529972).

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

81144648 is a wasteful number, since it uses less digits than its factorization.

81144648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86718 (or 86711 counting only the distinct ones).

The product of its digits is 24576, while the sum is 36.

The square root of 81144648 is about 9008.0324155722. The cubic root of 81144648 is about 432.9322716562.

The spelling of 81144648 in words is "eighty-one million, one hundred forty-four thousand, six hundred forty-eight".