81220110 has 32 divisors (see below), whose sum is σ = 195167232. Its totient is φ = 21632160.

The previous prime is 81220109. The next prime is 81220121. The reversal of 81220110 is 1102218.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81220110.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 42475 + ... + 44345.

It is an arithmetic number, because the mean of its divisors is an integer number (6098976).

Almost surely, 2^81220110 is an apocalyptic number.

81220110 is an abundant number, since it is smaller than the sum of its proper divisors (113947122).

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

81220110 is a wasteful number, since it uses less digits than its factorization.

81220110 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3328.

The product of its (nonzero) digits is 32, while the sum is 15.

The square root of 81220110 is about 9012.2200372605. The cubic root of 81220110 is about 433.0664345935.

Adding to 81220110 its reverse (1102218), we get a palindrome (82322328).

The spelling of 81220110 in words is "eighty-one million, two hundred twenty thousand, one hundred ten".