81618368 has 56 divisors (see below), whose sum is σ = 175552608. Its totient is φ = 37426176.

The previous prime is 81618353. The next prime is 81618389. The reversal of 81618368 is 86381618.

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 7 ways as a sum of consecutive naturals, for example, 218630 + ... + 219002.

It is an arithmetic number, because the mean of its divisors is an integer number (3134868).

Almost surely, 2^81618368 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 81618368, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87776304).

81618368 is an abundant number, since it is smaller than the sum of its proper divisors (93934240).

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

81618368 is a wasteful number, since it uses less digits than its factorization.

81618368 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 661 (or 651 counting only the distinct ones).

The product of its digits is 55296, while the sum is 41.

The square root of 81618368 is about 9034.2884611905. The cubic root of 81618368 is about 433.7731193262.

The spelling of 81618368 in words is "eighty-one million, six hundred eighteen thousand, three hundred sixty-eight".