81778845 has 16 divisors (see below), whose sum is σ = 130959360. Its totient is φ = 43577664.

The previous prime is 81778813. The next prime is 81778849. The reversal of 81778845 is 54887718.

It is not a de Polignac number, because 81778845 - 2⁵ = 81778813 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81778794 and 81778803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81778849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 29092 + ... + 31778.

It is an arithmetic number, because the mean of its divisors is an integer number (8184960).

Almost surely, 2^81778845 is an apocalyptic number.

It is an amenable number.

81778845 is a deficient number, since it is larger than the sum of its proper divisors (49180515).

81778845 is a wasteful number, since it uses less digits than its factorization.

81778845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4724.

The product of its digits is 501760, while the sum is 48.

The square root of 81778845 is about 9043.1656514740. The cubic root of 81778845 is about 434.0572262736.

The spelling of 81778845 in words is "eighty-one million, seven hundred seventy-eight thousand, eight hundred forty-five".