81317099 has 4 divisors (see below), whose sum is σ = 81335136. Its totient is φ = 81299064.

The previous prime is 81317077. The next prime is 81317129. The reversal of 81317099 is 99071318.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 81317099 - 2²⁰ = 80268523 is a prime.

It is a super-2 number, since 2×81317099² = 13224941179551602, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81317039) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4382 + ... + 13484.

It is an arithmetic number, because the mean of its divisors is an integer number (20333784).

Almost surely, 2^81317099 is an apocalyptic number.

81317099 is a deficient number, since it is larger than the sum of its proper divisors (18037).

81317099 is an equidigital number, since it uses as much as digits as its factorization.

81317099 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18036.

The product of its (nonzero) digits is 13608, while the sum is 38.

The square root of 81317099 is about 9017.5994033889. The cubic root of 81317099 is about 433.2387481266.

The spelling of 81317099 in words is "eighty-one million, three hundred seventeen thousand, ninety-nine".