81273251 has 4 divisors (see below), whose sum is σ = 81495072. Its totient is φ = 81051432.

The previous prime is 81273217. The next prime is 81273259. The reversal of 81273251 is 15237218.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15237218 = 2 ⋅7618609.

It is a cyclic number.

It is not a de Polignac number, because 81273251 - 2⁶ = 81273187 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81273259) 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, 110360 + ... + 111093.

It is an arithmetic number, because the mean of its divisors is an integer number (20373768).

Almost surely, 2^81273251 is an apocalyptic number.

81273251 is a deficient number, since it is larger than the sum of its proper divisors (221821).

81273251 is a wasteful number, since it uses less digits than its factorization.

81273251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221820.

The product of its digits is 3360, while the sum is 29.

The square root of 81273251 is about 9015.1678298299. The cubic root of 81273251 is about 433.1608634490.

The spelling of 81273251 in words is "eighty-one million, two hundred seventy-three thousand, two hundred fifty-one".