81677778 has 64 divisors (see below), whose sum is σ = 202245120. Its totient is φ = 21413952.

The previous prime is 81677773. The next prime is 81677779. The reversal of 81677778 is 87777618.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81677778.

It is not an unprimeable number, because it can be changed into a prime (81677773) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 123613 + ... + 124271.

It is an arithmetic number, because the mean of its divisors is an integer number (3160080).

Almost surely, 2^81677778 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81677778, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101122560).

81677778 is an abundant number, since it is smaller than the sum of its proper divisors (120567342).

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

81677778 is a wasteful number, since it uses less digits than its factorization.

81677778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 911.

The product of its digits is 921984, while the sum is 51.

The square root of 81677778 is about 9037.5758917975. The cubic root of 81677778 is about 433.8783416000.

The spelling of 81677778 in words is "eighty-one million, six hundred seventy-seven thousand, seven hundred seventy-eight".