81950915 has 4 divisors (see below), whose sum is σ = 98341104. Its totient is φ = 65560728.

The previous prime is 81950873. The next prime is 81950927. The reversal of 81950915 is 51905918.

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

It is a cyclic number.

It is not a de Polignac number, because 81950915 - 2⁶ = 81950851 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 (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8195087 + ... + 8195096.

It is an arithmetic number, because the mean of its divisors is an integer number (24585276).

Almost surely, 2^81950915 is an apocalyptic number.

81950915 is a deficient number, since it is larger than the sum of its proper divisors (16390189).

81950915 is a wasteful number, since it uses less digits than its factorization.

81950915 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16390188.

The product of its (nonzero) digits is 16200, while the sum is 38.

The square root of 81950915 is about 9052.6744666977. The cubic root of 81950915 is about 434.3614447403.

The spelling of 81950915 in words is "eighty-one million, nine hundred fifty thousand, nine hundred fifteen".