78865571 has 4 divisors (see below), whose sum is σ = 78915672. Its totient is φ = 78815472.

The previous prime is 78865531. The next prime is 78865573. The reversal of 78865571 is 17556887.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78865571 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78865573) 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, 22610 + ... + 25863.

It is an arithmetic number, because the mean of its divisors is an integer number (19728918).

Almost surely, 2^78865571 is an apocalyptic number.

78865571 is a deficient number, since it is larger than the sum of its proper divisors (50101).

78865571 is a wasteful number, since it uses less digits than its factorization.

78865571 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50100.

The product of its digits is 470400, while the sum is 47.

The square root of 78865571 is about 8880.6289754724. The cubic root of 78865571 is about 428.8405233472.

The spelling of 78865571 in words is "seventy-eight million, eight hundred sixty-five thousand, five hundred seventy-one".