81687247 has 4 divisors (see below), whose sum is σ = 81721960. Its totient is φ = 81652536.

The previous prime is 81687241. The next prime is 81687253. The reversal of 81687247 is 74278618.

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

It is an interprime number because it is at equal distance from previous prime (81687241) and next prime (81687253).

It is a cyclic number.

It is not a de Polignac number, because 81687247 - 2⁷ = 81687119 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 (81687241) 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, 13548 + ... + 18625.

It is an arithmetic number, because the mean of its divisors is an integer number (20430490).

Almost surely, 2^81687247 is an apocalyptic number.

81687247 is a deficient number, since it is larger than the sum of its proper divisors (34713).

81687247 is a wasteful number, since it uses less digits than its factorization.

81687247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34712.

The product of its digits is 150528, while the sum is 43.

The square root of 81687247 is about 9038.0997449685. The cubic root of 81687247 is about 433.8951076260.

The spelling of 81687247 in words is "eighty-one million, six hundred eighty-seven thousand, two hundred forty-seven".