81242547 has 4 divisors (see below), whose sum is σ = 108323400. Its totient is φ = 54161696.

The previous prime is 81242521. The next prime is 81242563. The reversal of 81242547 is 74524218.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81242547 - 2⁷ = 81242419 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81240547) 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, 13540422 + ... + 13540427.

It is an arithmetic number, because the mean of its divisors is an integer number (27080850).

Almost surely, 2^81242547 is an apocalyptic number.

81242547 is a deficient number, since it is larger than the sum of its proper divisors (27080853).

81242547 is a wasteful number, since it uses less digits than its factorization.

81242547 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27080852.

The product of its digits is 17920, while the sum is 33.

The square root of 81242547 is about 9013.4647611227. The cubic root of 81242547 is about 433.1063090244.

The spelling of 81242547 in words is "eighty-one million, two hundred forty-two thousand, five hundred forty-seven".