81181451 has 4 divisors (see below), whose sum is σ = 87426192. Its totient is φ = 74936712.

The previous prime is 81181447. The next prime is 81181459. The reversal of 81181451 is 15418118.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15418118 = 2 ⋅7709059.

It is a cyclic number.

It is not a de Polignac number, because 81181451 - 2² = 81181447 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81181459) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3122351 + ... + 3122376.

It is an arithmetic number, because the mean of its divisors is an integer number (21856548).

Almost surely, 2^81181451 is an apocalyptic number.

81181451 is a deficient number, since it is larger than the sum of its proper divisors (6244741).

81181451 is a wasteful number, since it uses less digits than its factorization.

81181451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6244740.

The product of its digits is 1280, while the sum is 29.

The square root of 81181451 is about 9010.0749719411. The cubic root of 81181451 is about 432.9977136316.

Adding to 81181451 its reverse (15418118), we get a palindrome (96599569).

The spelling of 81181451 in words is "eighty-one million, one hundred eighty-one thousand, four hundred fifty-one".