81582987 has 4 divisors (see below), whose sum is σ = 108777320. Its totient is φ = 54388656.

The previous prime is 81582971. The next prime is 81583027. The reversal of 81582987 is 78928518.

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

It is not a de Polignac number, because 81582987 - 2⁴ = 81582971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81582937) 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, 13597162 + ... + 13597167.

It is an arithmetic number, because the mean of its divisors is an integer number (27194330).

Almost surely, 2^81582987 is an apocalyptic number.

81582987 is a deficient number, since it is larger than the sum of its proper divisors (27194333).

81582987 is a wasteful number, since it uses less digits than its factorization.

81582987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27194332.

The product of its digits is 322560, while the sum is 48.

The square root of 81582987 is about 9032.3300980423. The cubic root of 81582987 is about 433.7104310479.

The spelling of 81582987 in words is "eighty-one million, five hundred eighty-two thousand, nine hundred eighty-seven".