81316788 has 48 divisors (see below), whose sum is σ = 218211840. Its totient is φ = 23086944.

The previous prime is 81316777. The next prime is 81316793. The reversal of 81316788 is 88761318.

It is a super-2 number, since 2×81316788² = 13224840021273888, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

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, 10723 + ... + 16661.

It is an arithmetic number, because the mean of its divisors is an integer number (4546080).

Almost surely, 2^81316788 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 81316788, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109105920).

81316788 is an abundant number, since it is smaller than the sum of its proper divisors (136895052).

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

81316788 is a wasteful number, since it uses less digits than its factorization.

81316788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6116 (or 6114 counting only the distinct ones).

The product of its digits is 64512, while the sum is 42.

The square root of 81316788 is about 9017.5821593152. The cubic root of 81316788 is about 433.2381958138.

The spelling of 81316788 in words is "eighty-one million, three hundred sixteen thousand, seven hundred eighty-eight".