81287064 has 160 divisors (see below), whose sum is σ = 247769280. Its totient is φ = 24800256.

The previous prime is 81287027. The next prime is 81287069. The reversal of 81287064 is 46078218.

It is a super-3 number, since 3×81287064³ (a number of 25 digits) contains 333 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81287069) by changing a digit.

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 39 ways as a sum of consecutive naturals, for example, 517674 + ... + 517830.

It is an arithmetic number, because the mean of its divisors is an integer number (1548558).

Almost surely, 2^81287064 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 81287064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123884640).

81287064 is an abundant number, since it is smaller than the sum of its proper divisors (166482216).

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

81287064 is a wasteful number, since it uses less digits than its factorization.

81287064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 239 (or 226 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 81287064 is about 9015.9338950549. The cubic root of 81287064 is about 433.1854017072.

The spelling of 81287064 in words is "eighty-one million, two hundred eighty-seven thousand, sixty-four".