78999971 has 4 divisors (see below), whose sum is σ = 79017792. Its totient is φ = 78982152.

The previous prime is 78999961. The next prime is 78999979. The reversal of 78999971 is 17999987.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78999971 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 78999971.

It is not an unprimeable number, because it can be changed into a prime (78999979) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3521 + ... + 13053.

It is an arithmetic number, because the mean of its divisors is an integer number (19754448).

Almost surely, 2^78999971 is an apocalyptic number.

78999971 is a deficient number, since it is larger than the sum of its proper divisors (17821).

78999971 is an equidigital number, since it uses as much as digits as its factorization.

78999971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17820.

The product of its digits is 2571912, while the sum is 59.

The square root of 78999971 is about 8888.1927859380. The cubic root of 78999971 is about 429.0839901987.

The spelling of 78999971 in words is "seventy-eight million, nine hundred ninety-nine thousand, nine hundred seventy-one".