81601776 has 80 divisors (see below), whose sum is σ = 239270400. Its totient is φ = 26615232.

The previous prime is 81601763. The next prime is 81601781. The reversal of 81601776 is 67710618.

It is a happy number.

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

It is a self number, because there is not a number n which added to its sum of digits gives 81601776.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 18295 + ... + 22313.

It is an arithmetic number, because the mean of its divisors is an integer number (2990880).

Almost surely, 2^81601776 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 81601776, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (119635200).

81601776 is an abundant number, since it is smaller than the sum of its proper divisors (157668624).

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

81601776 is a wasteful number, since it uses less digits than its factorization.

81601776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4083 (or 4071 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 36.

The square root of 81601776 is about 9033.3701352264. The cubic root of 81601776 is about 433.7437237726.

The spelling of 81601776 in words is "eighty-one million, six hundred one thousand, seven hundred seventy-six".