81630245 has 4 divisors (see below), whose sum is σ = 97956300. Its totient is φ = 65304192.

The previous prime is 81630181. The next prime is 81630247. The reversal of 81630245 is 54203618.

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 58262689 + 23367556 = 7633^2 + 4834^2 .

It is a cyclic number.

It is not a de Polignac number, because 81630245 - 2⁶ = 81630181 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81630247) 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, 8163020 + ... + 8163029.

It is an arithmetic number, because the mean of its divisors is an integer number (24489075).

Almost surely, 2^81630245 is an apocalyptic number.

It is an amenable number.

81630245 is a deficient number, since it is larger than the sum of its proper divisors (16326055).

81630245 is a wasteful number, since it uses less digits than its factorization.

81630245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16326054.

The product of its (nonzero) digits is 5760, while the sum is 29.

The square root of 81630245 is about 9034.9457663010. The cubic root of 81630245 is about 433.7941590080.

The spelling of 81630245 in words is "eighty-one million, six hundred thirty thousand, two hundred forty-five".