81697792 has 44 divisors (see below), whose sum is σ = 178187256. Its totient is φ = 37130240.

The previous prime is 81697747. The next prime is 81697799. The reversal of 81697792 is 29779618.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (44).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81697799) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7638 + ... + 14890.

Almost surely, 2^81697792 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 81697792, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (89093628).

81697792 is an abundant number, since it is smaller than the sum of its proper divisors (96489464).

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

81697792 is a wasteful number, since it uses less digits than its factorization.

81697792 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7284 (or 7266 counting only the distinct ones).

The product of its digits is 381024, while the sum is 49.

The square root of 81697792 is about 9038.6830899197. The cubic root of 81697792 is about 433.9137773173.

The spelling of 81697792 in words is "eighty-one million, six hundred ninety-seven thousand, seven hundred ninety-two".