81279872 has 48 divisors (see below), whose sum is σ = 170992800. Its totient is φ = 38479104.

The previous prime is 81279829. The next prime is 81279881. The reversal of 81279872 is 27897218.

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 5 ways as a sum of consecutive naturals, for example, 45329 + ... + 47087.

It is an arithmetic number, because the mean of its divisors is an integer number (3562350).

Almost surely, 2^81279872 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 81279872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (85496400).

81279872 is an abundant number, since it is smaller than the sum of its proper divisors (89712928).

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

81279872 is a wasteful number, since it uses less digits than its factorization.

81279872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1811 (or 1780 counting only the distinct ones).

The product of its digits is 112896, while the sum is 44.

The square root of 81279872 is about 9015.5350368128. The cubic root of 81279872 is about 433.1726257454.

The spelling of 81279872 in words is "eighty-one million, two hundred seventy-nine thousand, eight hundred seventy-two".