81671287 has 4 divisors (see below), whose sum is σ = 82314496. Its totient is φ = 81028080.

The previous prime is 81671273. The next prime is 81671299. The reversal of 81671287 is 78217618.

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 81671287 - 2¹⁵ = 81638519 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 (81671207) 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, 321414 + ... + 321667.

It is an arithmetic number, because the mean of its divisors is an integer number (20578624).

Almost surely, 2^81671287 is an apocalyptic number.

81671287 is a deficient number, since it is larger than the sum of its proper divisors (643209).

81671287 is a wasteful number, since it uses less digits than its factorization.

81671287 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643208.

The product of its digits is 37632, while the sum is 40.

The square root of 81671287 is about 9037.2167728787. The cubic root of 81671287 is about 433.8668477396.

The spelling of 81671287 in words is "eighty-one million, six hundred seventy-one thousand, two hundred eighty-seven".