81756416 has 72 divisors (see below), whose sum is σ = 191024064. Its totient is φ = 34191360.

The previous prime is 81756407. The next prime is 81756427. The reversal of 81756416 is 61465718.

It is a super-2 number, since 2×81756416² = 13368223114330112, which contains 22 as substring.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 81756416.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76526 + ... + 77586.

It is an arithmetic number, because the mean of its divisors is an integer number (2653112).

Almost surely, 2^81756416 is an apocalyptic number.

81756416 is a gapful number since it is divisible by the number (86) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81756416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (95512032).

81756416 is an abundant number, since it is smaller than the sum of its proper divisors (109267648).

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

81756416 is a wasteful number, since it uses less digits than its factorization.

81756416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1127 (or 1113 counting only the distinct ones).

The product of its digits is 40320, while the sum is 38.

The square root of 81756416 is about 9041.9254586620. The cubic root of 81756416 is about 434.0175405427.

The spelling of 81756416 in words is "eighty-one million, seven hundred fifty-six thousand, four hundred sixteen".