81279539 has 16 divisors (see below), whose sum is σ = 92911104. Its totient is φ = 70382400.

The previous prime is 81279529. The next prime is 81279553. The reversal of 81279539 is 93597218.

It is not a de Polignac number, because 81279539 - 2¹² = 81275443 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81279539.

It is not an unprimeable number, because it can be changed into a prime (81279529) by changing a digit.

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, 78167 + ... + 79199.

It is an arithmetic number, because the mean of its divisors is an integer number (5806944).

Almost surely, 2^81279539 is an apocalyptic number.

81279539 is a deficient number, since it is larger than the sum of its proper divisors (11631565).

81279539 is a wasteful number, since it uses less digits than its factorization.

81279539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1378.

The product of its digits is 136080, while the sum is 44.

The square root of 81279539 is about 9015.5165686720. The cubic root of 81279539 is about 433.1720341816.

It can be divided in two parts, 81279 and 539, that added together give a palindrome (81818).

The spelling of 81279539 in words is "eighty-one million, two hundred seventy-nine thousand, five hundred thirty-nine".