81864648 has 64 divisors (see below), whose sum is σ = 231724800. Its totient is φ = 26769600.

The previous prime is 81864637. The next prime is 81864677. The reversal of 81864648 is 84646818.

81864648 is a `hidden beast` number, since 8 + 186 + 464 + 8 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7873 + ... + 15023.

It is an arithmetic number, because the mean of its divisors is an integer number (3620700).

Almost surely, 2^81864648 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 81864648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (115862400).

81864648 is an abundant number, since it is smaller than the sum of its proper divisors (149860152).

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

81864648 is a wasteful number, since it uses less digits than its factorization.

81864648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7219 (or 7209 counting only the distinct ones).

The product of its digits is 294912, while the sum is 45.

The square root of 81864648 is about 9047.9084876009. The cubic root of 81864648 is about 434.2089786182.

The spelling of 81864648 in words is "eighty-one million, eight hundred sixty-four thousand, six hundred forty-eight".