78181818 has 32 divisors (see below), whose sum is σ = 183701952. Its totient is φ = 21868800.

The previous prime is 78181811. The next prime is 78181819. The reversal of 78181818 is 81818187.

It is a super-2 number, since 2×78181818² = 12224793331570248, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

78181818 is a modest number, since divided by 181818 gives 78 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 78181818.

It is not an unprimeable number, because it can be changed into a prime (78181811) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 44703 + ... + 46418.

It is an arithmetic number, because the mean of its divisors is an integer number (5740686).

Almost surely, 2^78181818 is an apocalyptic number.

78181818 is a gapful number since it is divisible by the number (78) formed by its first and last digit.

78181818 is an abundant number, since it is smaller than the sum of its proper divisors (105520134).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

78181818 is a wasteful number, since it uses less digits than its factorization.

78181818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91150.

The product of its digits is 28672, while the sum is 42.

The square root of 78181818 is about 8842.0482921097. The cubic root of 78181818 is about 427.5975961301.

The spelling of 78181818 in words is "seventy-eight million, one hundred eighty-one thousand, eight hundred eighteen".