81687558 has 8 divisors (see below), whose sum is σ = 163375128. Its totient is φ = 27229184.

The previous prime is 81687523. The next prime is 81687563. The reversal of 81687558 is 85578618.

It is a sphenic number, since it is the product of 3 distinct primes.

81687558 is an admirable number.

It is a congruent number.

It is an unprimeable number.

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, 6807291 + ... + 6807302.

It is an arithmetic number, because the mean of its divisors is an integer number (20421891).

Almost surely, 2^81687558 is an apocalyptic number.

81687558 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81687558 is a wasteful number, since it uses less digits than its factorization.

81687558 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13614598.

The product of its digits is 537600, while the sum is 48.

The square root of 81687558 is about 9038.1169498961. The cubic root of 81687558 is about 433.8956582677.

The spelling of 81687558 in words is "eighty-one million, six hundred eighty-seven thousand, five hundred fifty-eight".