81928879 has 2 divisors, whose sum is σ = 81928880. Its totient is φ = 81928878.

The previous prime is 81928871. The next prime is 81928901. The reversal of 81928879 is 97882918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81928879 - 2³ = 81928871 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81928871) 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 as a sum of consecutive naturals, namely, 40964439 + 40964440.

It is an arithmetic number, because the mean of its divisors is an integer number (40964440).

Almost surely, 2^81928879 is an apocalyptic number.

81928879 is a deficient number, since it is larger than the sum of its proper divisors (1).

81928879 is an equidigital number, since it uses as much as digits as its factorization.

81928879 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 580608, while the sum is 52.

The square root of 81928879 is about 9051.4572859844. The cubic root of 81928879 is about 434.3225090480.

It can be divided in two parts, 8192 and 8879, that added together give a palindrome (17071).

The spelling of 81928879 in words is "eighty-one million, nine hundred twenty-eight thousand, eight hundred seventy-nine".