79999999 has 4 divisors (see below), whose sum is σ = 80048520.
Its totient is φ = 79951480.
The previous prime is 79999987. The next prime is 80000023. The reversal of 79999999 is 99999997.
It can be divided in two parts, 7999999 and 9, that added together give a palindrome (8000008).
It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99999997 = 1297 ⋅77101.
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-79999999 is a prime.
It is a Duffinian number.
79999999 is a modest number, since divided by 9999 gives 7999 as remainder.
It is a plaindrome in base 10.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (79996999) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (17) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21697 + ... + 25114.
It is an arithmetic number, because the mean of its divisors is an integer number (20012130).
Almost surely, 279999999 is an apocalyptic number.
79999999 is a deficient number, since it is larger than the sum of its proper divisors (48521).
79999999 is a wasteful number, since it uses less digits than its factorization.
79999999 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 48520.
The product of its digits is 33480783, while the sum is 70.
The square root of 79999999 is about 8944.2718540975.
The cubic root of 79999999 is about 430.8869362110.
The spelling of 79999999 in words is "seventy-nine million, nine hundred ninety-nine thousand, nine hundred ninety-nine".