81840151 has 4 divisors (see below), whose sum is σ = 82075000. Its totient is φ = 81605304.

The previous prime is 81840149. The next prime is 81840167. The reversal of 81840151 is 15104818.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15104818 = 2 ⋅7552409.

It is a cyclic number.

It is not a de Polignac number, because 81840151 - 2¹ = 81840149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81840131) 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, 116901 + ... + 117598.

It is an arithmetic number, because the mean of its divisors is an integer number (20518750).

Almost surely, 2^81840151 is an apocalyptic number.

81840151 is a deficient number, since it is larger than the sum of its proper divisors (234849).

81840151 is a wasteful number, since it uses less digits than its factorization.

81840151 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 234848.

The product of its (nonzero) digits is 1280, while the sum is 28.

The square root of 81840151 is about 9046.5546480414. The cubic root of 81840151 is about 434.1656637126.

Adding to 81840151 its reverse (15104818), we get a palindrome (96944969).

The spelling of 81840151 in words is "eighty-one million, eight hundred forty thousand, one hundred fifty-one".