78631818121 has 4 divisors (see below), whose sum is σ = 78640866000. Its totient is φ = 78622770244.

The previous prime is 78631818073. The next prime is 78631818151. The reversal of 78631818121 is 12181813687.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12181813687 = 41 ⋅297117407.

It is a cyclic number.

It is not a de Polignac number, because 78631818121 - 2⁷ = 78631817993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78631818151) 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, 4510891 + ... + 4528288.

It is an arithmetic number, because the mean of its divisors is an integer number (19660216500).

Almost surely, 2^78631818121 is an apocalyptic number.

It is an amenable number.

78631818121 is a deficient number, since it is larger than the sum of its proper divisors (9047879).

78631818121 is an equidigital number, since it uses as much as digits as its factorization.

78631818121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9047878.

The product of its digits is 129024, while the sum is 46.

The spelling of 78631818121 in words is "seventy-eight billion, six hundred thirty-one million, eight hundred eighteen thousand, one hundred twenty-one".