81222839 has 4 divisors (see below), whose sum is σ = 81264456. Its totient is φ = 81181224.

The previous prime is 81222809. The next prime is 81222859. The reversal of 81222839 is 93822218.

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-81222839 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81222799 and 81222808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81222809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17729 + ... + 21834.

It is an arithmetic number, because the mean of its divisors is an integer number (20316114).

Almost surely, 2^81222839 is an apocalyptic number.

81222839 is a deficient number, since it is larger than the sum of its proper divisors (41617).

81222839 is a wasteful number, since it uses less digits than its factorization.

81222839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41616.

The product of its digits is 13824, while the sum is 35.

The square root of 81222839 is about 9012.3714415241. The cubic root of 81222839 is about 433.0712848909.

The spelling of 81222839 in words is "eighty-one million, two hundred twenty-two thousand, eight hundred thirty-nine".