81611712 has 280 divisors, whose sum is σ = 299472096. Its totient is φ = 21399552.

The previous prime is 81611683. The next prime is 81611723. The reversal of 81611712 is 21711618.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

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 39 ways as a sum of consecutive naturals, for example, 471658 + ... + 471830.

Almost surely, 2^81611712 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 81611712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (149736048).

81611712 is an abundant number, since it is smaller than the sum of its proper divisors (217860384).

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

81611712 is a wasteful number, since it uses less digits than its factorization.

81611712 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 217 (or 198 counting only the distinct ones).

The product of its digits is 672, while the sum is 27.

The square root of 81611712 is about 9033.9200793454. The cubic root of 81611712 is about 433.7613275673.

The spelling of 81611712 in words is "eighty-one million, six hundred eleven thousand, seven hundred twelve".