81899387 has 8 divisors (see below), whose sum is σ = 86936400. Its totient is φ = 76886784.

The previous prime is 81899381. The next prime is 81899399. The reversal of 81899387 is 78399818.

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

It is not a de Polignac number, because 81899387 - 2⁸ = 81899131 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81899381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1064 + ... + 12842.

It is an arithmetic number, because the mean of its divisors is an integer number (10867050).

Almost surely, 2^81899387 is an apocalyptic number.

81899387 is a deficient number, since it is larger than the sum of its proper divisors (5037013).

81899387 is a wasteful number, since it uses less digits than its factorization.

81899387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12205.

The product of its digits is 870912, while the sum is 53.

The square root of 81899387 is about 9049.8280094154. The cubic root of 81899387 is about 434.2703883271.

It can be divided in two parts, 8189 and 9387, that added together give a cube (17576 = 26³).

The spelling of 81899387 in words is "eighty-one million, eight hundred ninety-nine thousand, three hundred eighty-seven".