81287187 has 16 divisors (see below), whose sum is σ = 117173760. Its totient is φ = 49950432.

The previous prime is 81287069. The next prime is 81287189. The reversal of 81287187 is 78178218.

It is not a de Polignac number, because 81287187 - 2¹⁴ = 81270803 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81287189) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17163 + ... + 21380.

It is an arithmetic number, because the mean of its divisors is an integer number (7323360).

Almost surely, 2^81287187 is an apocalyptic number.

81287187 is a deficient number, since it is larger than the sum of its proper divisors (35886573).

81287187 is a wasteful number, since it uses less digits than its factorization.

81287187 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38602.

The product of its digits is 50176, while the sum is 42.

The square root of 81287187 is about 9015.9407163091. The cubic root of 81287187 is about 433.1856201995.

The spelling of 81287187 in words is "eighty-one million, two hundred eighty-seven thousand, one hundred eighty-seven".