81395712 has 144 divisors (see below), whose sum is σ = 251657280. Its totient is φ = 25952256.

The previous prime is 81395683. The next prime is 81395729. The reversal of 81395712 is 21759318.

81395712 is a `hidden beast` number, since 81 + 3 + 9 + 571 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

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

Its product of digits (15120) is a multiple of the sum of its prime divisors (28).

It is a congruent number.

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, 3538933 + ... + 3538955.

It is an arithmetic number, because the mean of its divisors is an integer number (1747620).

Almost surely, 2^81395712 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 81395712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (125828640).

81395712 is an abundant number, since it is smaller than the sum of its proper divisors (170261568).

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

81395712 is an frugal number, since it uses more digits than its factorization.

81395712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66 (or 28 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 81395712 is about 9021.9572155935. The cubic root of 81395712 is about 433.3783138055.

The spelling of 81395712 in words is "eighty-one million, three hundred ninety-five thousand, seven hundred twelve".