78989899 has 4 divisors (see below), whose sum is σ = 79189264. Its totient is φ = 78790536.

The previous prime is 78989893. The next prime is 78989909. The reversal of 78989899 is 99898987.

It is a happy number.

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 78989899 - 2²¹ = 76892747 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78989893) 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, 99087 + ... + 99880.

It is an arithmetic number, because the mean of its divisors is an integer number (19797316).

Almost surely, 2^78989899 is an apocalyptic number.

78989899 is a deficient number, since it is larger than the sum of its proper divisors (199365).

78989899 is a wasteful number, since it uses less digits than its factorization.

78989899 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199364.

The product of its digits is 23514624, while the sum is 67.

The square root of 78989899 is about 8887.6261735066. The cubic root of 78989899 is about 429.0657542526.

The spelling of 78989899 in words is "seventy-eight million, nine hundred eighty-nine thousand, eight hundred ninety-nine".