81816235 has 4 divisors (see below), whose sum is σ = 98179488. Its totient is φ = 65452984.

The previous prime is 81816233. The next prime is 81816239. The reversal of 81816235 is 53261818.

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

It is a cyclic number.

It is not a de Polignac number, because 81816235 - 2¹ = 81816233 is a prime.

It is a super-3 number, since 3×81816235³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81816235.

It is not an unprimeable number, because it can be changed into a prime (81816233) 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 3 ways as a sum of consecutive naturals, for example, 8181619 + ... + 8181628.

It is an arithmetic number, because the mean of its divisors is an integer number (24544872).

Almost surely, 2^81816235 is an apocalyptic number.

81816235 is a deficient number, since it is larger than the sum of its proper divisors (16363253).

81816235 is a wasteful number, since it uses less digits than its factorization.

81816235 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16363252.

The product of its digits is 11520, while the sum is 34.

The square root of 81816235 is about 9045.2327222687. The cubic root of 81816235 is about 434.1233677755.

The spelling of 81816235 in words is "eighty-one million, eight hundred sixteen thousand, two hundred thirty-five".