81275220 has 144 divisors (see below), whose sum is σ = 271514880. Its totient is φ = 19554048.

The previous prime is 81275219. The next prime is 81275231. The reversal of 81275220 is 2257218.

It is a super-2 number, since 2×81275220² = 13211322772096800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 109611 + ... + 110349.

It is an arithmetic number, because the mean of its divisors is an integer number (1885520).

Almost surely, 2^81275220 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81275220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (135757440).

81275220 is an abundant number, since it is smaller than the sum of its proper divisors (190239660).

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

81275220 is a wasteful number, since it uses less digits than its factorization.

81275220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 814 (or 809 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 81275220 is about 9015.2770340129. The cubic root of 81275220 is about 433.1643614709.

The spelling of 81275220 in words is "eighty-one million, two hundred seventy-five thousand, two hundred twenty".