81950917 has 4 divisors (see below), whose sum is σ = 81969580. Its totient is φ = 81932256.

The previous prime is 81950873. The next prime is 81950927. The reversal of 81950917 is 71905918.

It is a happy number.

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 57289761 + 24661156 = 7569^2 + 4966^2 .

It is a cyclic number.

It is not a de Polignac number, because 81950917 - 2¹¹ = 81948869 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81950917.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81950927) 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, 1273 + ... + 12865.

It is an arithmetic number, because the mean of its divisors is an integer number (20492395).

Almost surely, 2^81950917 is an apocalyptic number.

It is an amenable number.

81950917 is a deficient number, since it is larger than the sum of its proper divisors (18663).

81950917 is a wasteful number, since it uses less digits than its factorization.

81950917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18662.

The product of its (nonzero) digits is 22680, while the sum is 40.

The square root of 81950917 is about 9052.6745771623. The cubic root of 81950917 is about 434.3614482738.

The spelling of 81950917 in words is "eighty-one million, nine hundred fifty thousand, nine hundred seventeen".