81786245 has 4 divisors (see below), whose sum is σ = 98143500. Its totient is φ = 65428992.

The previous prime is 81786233. The next prime is 81786247. The reversal of 81786245 is 54268718.

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

It can be written as a sum of positive squares in 2 ways, for example, as 48804196 + 32982049 = 6986^2 + 5743^2 .

It is a cyclic number.

It is not a de Polignac number, because 81786245 - 2⁶ = 81786181 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81786247) 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 3 ways as a sum of consecutive naturals, for example, 8178620 + ... + 8178629.

It is an arithmetic number, because the mean of its divisors is an integer number (24535875).

Almost surely, 2^81786245 is an apocalyptic number.

It is an amenable number.

81786245 is a deficient number, since it is larger than the sum of its proper divisors (16357255).

81786245 is a wasteful number, since it uses less digits than its factorization.

81786245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16357254.

The product of its digits is 107520, while the sum is 41.

The square root of 81786245 is about 9043.5747909773. The cubic root of 81786245 is about 434.0703181948.

The spelling of 81786245 in words is "eighty-one million, seven hundred eighty-six thousand, two hundred forty-five".