81368064 has 154 divisors (see below), whose sum is σ = 246110810. Its totient is φ = 26873856.

The previous prime is 81368047. The next prime is 81368117. The reversal of 81368064 is 46086318.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 74649600 + 6718464 = 8640^2 + 2592^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 746442 + ... + 746550.

Almost surely, 2^81368064 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 81368064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123055405).

81368064 is an abundant number, since it is smaller than the sum of its proper divisors (164742746).

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

81368064 is an equidigital number, since it uses as much as digits as its factorization.

81368064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147 (or 114 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The square root of 81368064 is about 9020.4248236987. The cubic root of 81368064 is about 433.3292391461.

The spelling of 81368064 in words is "eighty-one million, three hundred sixty-eight thousand, sixty-four".