81287388 has 144 divisors (see below), whose sum is σ = 262545920. Its totient is φ = 21415104.

The previous prime is 81287383. The next prime is 81287407. The reversal of 81287388 is 88378218.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81287383) 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 47 ways as a sum of consecutive naturals, for example, 87993 + ... + 88911.

Almost surely, 2^81287388 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 81287388, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (131272960).

81287388 is an abundant number, since it is smaller than the sum of its proper divisors (181258532).

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

81287388 is a wasteful number, since it uses less digits than its factorization.

81287388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 958 (or 944 counting only the distinct ones).

The product of its digits is 172032, while the sum is 45.

The square root of 81287388 is about 9015.9518632255. The cubic root of 81287388 is about 433.1859772473.

The spelling of 81287388 in words is "eighty-one million, two hundred eighty-seven thousand, three hundred eighty-eight".