81612151 has 4 divisors (see below), whose sum is σ = 83510152. Its totient is φ = 79714152.

The previous prime is 81612143. The next prime is 81612161. The reversal of 81612151 is 15121618.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15121618 = 2 ⋅7560809.

It is a cyclic number.

It is not a de Polignac number, because 81612151 - 2³ = 81612143 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 (81612101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 948936 + ... + 949021.

It is an arithmetic number, because the mean of its divisors is an integer number (20877538).

Almost surely, 2^81612151 is an apocalyptic number.

81612151 is a deficient number, since it is larger than the sum of its proper divisors (1898001).

81612151 is a wasteful number, since it uses less digits than its factorization.

81612151 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1898000.

The product of its digits is 480, while the sum is 25.

The square root of 81612151 is about 9033.9443766275. The cubic root of 81612151 is about 433.7621053187.

Adding to 81612151 its reverse (15121618), we get a palindrome (96733769).

The spelling of 81612151 in words is "eighty-one million, six hundred twelve thousand, one hundred fifty-one".