81289215 has 24 divisors (see below), whose sum is σ = 161030688. Its totient is φ = 37160640.

The previous prime is 81289181. The next prime is 81289231. The reversal of 81289215 is 51298218.

It is not a de Polignac number, because 81289215 - 2⁶ = 81289151 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81289215.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 128716 + ... + 129345.

It is an arithmetic number, because the mean of its divisors is an integer number (6709612).

Almost surely, 2^81289215 is an apocalyptic number.

81289215 is a deficient number, since it is larger than the sum of its proper divisors (79741473).

81289215 is a wasteful number, since it uses less digits than its factorization.

81289215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 258079 (or 258076 counting only the distinct ones).

The product of its digits is 11520, while the sum is 36.

The square root of 81289215 is about 9016.0531830730. The cubic root of 81289215 is about 433.1892226251.

The spelling of 81289215 in words is "eighty-one million, two hundred eighty-nine thousand, two hundred fifteen".