81797072 has 60 divisors (see below), whose sum is σ = 186361956. Its totient is φ = 34675200.

The previous prime is 81797063. The next prime is 81797117. The reversal of 81797072 is 27079718.

It can be written as a sum of positive squares in 2 ways, for example, as 78783376 + 3013696 = 8876^2 + 1736^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 78668 + ... + 79700.

Almost surely, 2^81797072 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 81797072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (93180978).

81797072 is an abundant number, since it is smaller than the sum of its proper divisors (104564884).

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

81797072 is a wasteful number, since it uses less digits than its factorization.

81797072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1156 (or 1143 counting only the distinct ones).

The product of its (nonzero) digits is 49392, while the sum is 41.

The square root of 81797072 is about 9044.1733729512. The cubic root of 81797072 is about 434.0894716681.

It can be divided in two parts, 8179 and 7072, that added together give a palindrome (15251).

The spelling of 81797072 in words is "eighty-one million, seven hundred ninety-seven thousand, seventy-two".