81322399 has 4 divisors (see below), whose sum is σ = 81525600. Its totient is φ = 81119200.

The previous prime is 81322357. The next prime is 81322427. The reversal of 81322399 is 99322318.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81322399 is a prime.

It is a super-2 number, since 2×81322399² = 13226665158230402, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81322099) 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, 100999 + ... + 101800.

It is an arithmetic number, because the mean of its divisors is an integer number (20381400).

Almost surely, 2^81322399 is an apocalyptic number.

81322399 is a deficient number, since it is larger than the sum of its proper divisors (203201).

81322399 is a wasteful number, since it uses less digits than its factorization.

81322399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 203200.

The product of its digits is 23328, while the sum is 37.

The square root of 81322399 is about 9017.8932683859. The cubic root of 81322399 is about 433.2481603146.

The spelling of 81322399 in words is "eighty-one million, three hundred twenty-two thousand, three hundred ninety-nine".