81788225 has 18 divisors (see below), whose sum is σ = 103691094. Its totient is φ = 63995200.

The previous prime is 81788197. The next prime is 81788233. The reversal of 81788225 is 52288718.

It can be written as a sum of positive squares in 3 ways, for example, as 3713329 + 78074896 = 1927^2 + 8836^2 .

It is not a de Polignac number, because 81788225 - 2²⁶ = 14679361 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 17 ways as a sum of consecutive naturals, for example, 54485 + ... + 55965.

Almost surely, 2^81788225 is an apocalyptic number.

It is an amenable number.

81788225 is a deficient number, since it is larger than the sum of its proper divisors (21902869).

81788225 is a wasteful number, since it uses less digits than its factorization.

81788225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1585 (or 1533 counting only the distinct ones).

The product of its digits is 71680, while the sum is 41.

The square root of 81788225 is about 9043.6842603001. The cubic root of 81788225 is about 434.0738210344.

The spelling of 81788225 in words is "eighty-one million, seven hundred eighty-eight thousand, two hundred twenty-five".