81222020 has 24 divisors (see below), whose sum is σ = 186072768. Its totient is φ = 29535200.

The previous prime is 81222019. The next prime is 81222059. The reversal of 81222020 is 2022218.

It is a self number, because there is not a number n which added to its sum of digits gives 81222020.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 184376 + ... + 184815.

It is an arithmetic number, because the mean of its divisors is an integer number (7753032).

Almost surely, 2^81222020 is an apocalyptic number.

It is an amenable number.

81222020 is an abundant number, since it is smaller than the sum of its proper divisors (104850748).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81222020 is a wasteful number, since it uses less digits than its factorization.

81222020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 369211 (or 369209 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 17.

The square root of 81222020 is about 9012.3260038683. The cubic root of 81222020 is about 433.0698292799.

Adding to 81222020 its reverse (2022218), we get a palindrome (83244238).

The spelling of 81222020 in words is "eighty-one million, two hundred twenty-two thousand, twenty".