81315249 has 4 divisors (see below), whose sum is σ = 108420336. Its totient is φ = 54210164.

The previous prime is 81315229. The next prime is 81315251. The reversal of 81315249 is 94251318.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81315249 - 2⁷ = 81315121 is a prime.

It is a super-2 number, since 2×81315249² = 13224339439864002, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81315229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13552539 + ... + 13552544.

It is an arithmetic number, because the mean of its divisors is an integer number (27105084).

Almost surely, 2^81315249 is an apocalyptic number.

It is an amenable number.

81315249 is a deficient number, since it is larger than the sum of its proper divisors (27105087).

81315249 is a wasteful number, since it uses less digits than its factorization.

81315249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27105086.

The product of its digits is 8640, while the sum is 33.

The square root of 81315249 is about 9017.4968256163. The cubic root of 81315249 is about 433.2354626439.

The spelling of 81315249 in words is "eighty-one million, three hundred fifteen thousand, two hundred forty-nine".