78171818 has 12 divisors (see below), whose sum is σ = 118343238. Its totient is φ = 38727360.

The previous prime is 78171817. The next prime is 78171823. The reversal of 78171818 is 81817187.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 40998409 + 37173409 = 6403^2 + 6097^2 .

It is a super-2 number, since 2×78171818² = 12221666258850248, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78171811) 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 5 ways as a sum of consecutive naturals, for example, 24008 + ... + 27068.

Almost surely, 2^78171818 is an apocalyptic number.

78171818 is a deficient number, since it is larger than the sum of its proper divisors (40171420).

78171818 is a wasteful number, since it uses less digits than its factorization.

78171818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3289 (or 3176 counting only the distinct ones).

The product of its digits is 25088, while the sum is 41.

The square root of 78171818 is about 8841.4827941924. The cubic root of 78171818 is about 427.5793644474.

The spelling of 78171818 in words is "seventy-eight million, one hundred seventy-one thousand, eight hundred eighteen".