81811499 has 16 divisors (see below), whose sum is σ = 104375040. Its totient is φ = 62264160.

The previous prime is 81811447. The next prime is 81811517. The reversal of 81811499 is 99411818.

It is not a de Polignac number, because 81811499 - 2¹² = 81807403 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81811409) 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, 9044 + ... + 15665.

It is an arithmetic number, because the mean of its divisors is an integer number (6523440).

Almost surely, 2^81811499 is an apocalyptic number.

81811499 is a deficient number, since it is larger than the sum of its proper divisors (22563541).

81811499 is a wasteful number, since it uses less digits than its factorization.

81811499 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24770.

The product of its digits is 20736, while the sum is 41.

The square root of 81811499 is about 9044.9709231152. The cubic root of 81811499 is about 434.1149910846.

The spelling of 81811499 in words is "eighty-one million, eight hundred eleven thousand, four hundred ninety-nine".