81878279 has 4 divisors (see below), whose sum is σ = 93575184. Its totient is φ = 70181376.

The previous prime is 81878261. The next prime is 81878311. The reversal of 81878279 is 97287818.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81878279 - 2¹⁶ = 81812743 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81878179) 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 3 ways as a sum of consecutive naturals, for example, 5848442 + ... + 5848455.

It is an arithmetic number, because the mean of its divisors is an integer number (23393796).

Almost surely, 2^81878279 is an apocalyptic number.

81878279 is a deficient number, since it is larger than the sum of its proper divisors (11696905).

81878279 is a wasteful number, since it uses less digits than its factorization.

81878279 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11696904.

The product of its digits is 451584, while the sum is 50.

The square root of 81878279 is about 9048.6617242551. The cubic root of 81878279 is about 434.2330768269.

It can be divided in two parts, 818 and 78279, that added together give a palindrome (79097).

The spelling of 81878279 in words is "eighty-one million, eight hundred seventy-eight thousand, two hundred seventy-nine".