81285787 has 8 divisors (see below), whose sum is σ = 88962480. Its totient is φ = 73656960.

The previous prime is 81285767. The next prime is 81285793. The reversal of 81285787 is 78758218.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 81285787 - 2¹⁵ = 81253019 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81285727) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 8362 + ... + 15247.

It is an arithmetic number, because the mean of its divisors is an integer number (11120310).

Almost surely, 2^81285787 is an apocalyptic number.

81285787 is a deficient number, since it is larger than the sum of its proper divisors (7676693).

81285787 is a wasteful number, since it uses less digits than its factorization.

81285787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23933.

The product of its digits is 250880, while the sum is 46.

The square root of 81285787 is about 9015.8630757127. The cubic root of 81285787 is about 433.1831332829.

The spelling of 81285787 in words is "eighty-one million, two hundred eighty-five thousand, seven hundred eighty-seven".