81352581 has 8 divisors (see below), whose sum is σ = 109998144. Its totient is φ = 53471040.

The previous prime is 81352577. The next prime is 81352619. The reversal of 81352581 is 18525318.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81352581 - 2² = 81352577 is a prime.

It is a super-3 number, since 3×81352581³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81352501) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 190756 + ... + 191181.

It is an arithmetic number, because the mean of its divisors is an integer number (13749768).

Almost surely, 2^81352581 is an apocalyptic number.

It is an amenable number.

81352581 is a deficient number, since it is larger than the sum of its proper divisors (28645563).

81352581 is a wasteful number, since it uses less digits than its factorization.

81352581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 382011.

The product of its digits is 9600, while the sum is 33.

The square root of 81352581 is about 9019.5665638655. The cubic root of 81352581 is about 433.3017522678.

Adding to 81352581 its reverse (18525318), we get a palindrome (99877899).

The spelling of 81352581 in words is "eighty-one million, three hundred fifty-two thousand, five hundred eighty-one".