81354581 has 16 divisors (see below), whose sum is σ = 103792128. Its totient is φ = 61916400.

The previous prime is 81354577. The next prime is 81354589. The reversal of 81354581 is 18545318.

It is not a de Polignac number, because 81354581 - 2² = 81354577 is a prime.

It is a super-2 number, since 2×81354581² = 13237135699371122, which contains 22 as substring.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81354589) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8975 + ... + 15596.

It is an arithmetic number, because the mean of its divisors is an integer number (6487008).

Almost surely, 2^81354581 is an apocalyptic number.

It is an amenable number.

81354581 is a deficient number, since it is larger than the sum of its proper divisors (22437547).

81354581 is a wasteful number, since it uses less digits than its factorization.

81354581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24632.

The product of its digits is 19200, while the sum is 35.

The square root of 81354581 is about 9019.6774332567. The cubic root of 81354581 is about 433.3053030521.

Adding to 81354581 its reverse (18545318), we get a palindrome (99899899).

The spelling of 81354581 in words is "eighty-one million, three hundred fifty-four thousand, five hundred eighty-one".