81879321 has 4 divisors (see below), whose sum is σ = 109172432. Its totient is φ = 54586212.

The previous prime is 81879299. The next prime is 81879331. The reversal of 81879321 is 12397818.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 81879321 - 2⁶ = 81879257 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81879321.

It is not an unprimeable number, because it can be changed into a prime (81879331) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 13646551 + ... + 13646556.

It is an arithmetic number, because the mean of its divisors is an integer number (27293108).

Almost surely, 2^81879321 is an apocalyptic number.

It is an amenable number.

81879321 is a deficient number, since it is larger than the sum of its proper divisors (27293111).

81879321 is a wasteful number, since it uses less digits than its factorization.

81879321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27293110.

The product of its digits is 24192, while the sum is 39.

The square root of 81879321 is about 9048.7193016471. The cubic root of 81879321 is about 434.2349188659.

The spelling of 81879321 in words is "eighty-one million, eight hundred seventy-nine thousand, three hundred twenty-one".