78418666 has 4 divisors (see below), whose sum is σ = 117628002. Its totient is φ = 39209332.

The previous prime is 78418601. The next prime is 78418673. The reversal of 78418666 is 66681487.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 75429225 + 2989441 = 8685^2 + 1729^2 .

It is a super-2 number, since 2×78418666² = 12298974354439112, which contains 22 as substring.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 19604665 + ... + 19604668.

Almost surely, 2^78418666 is an apocalyptic number.

78418666 is a deficient number, since it is larger than the sum of its proper divisors (39209336).

78418666 is a wasteful number, since it uses less digits than its factorization.

78418666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39209335.

The product of its digits is 387072, while the sum is 46.

The square root of 78418666 is about 8855.4314406470. The cubic root of 78418666 is about 428.0289561741.

The spelling of 78418666 in words is "seventy-eight million, four hundred eighteen thousand, six hundred sixty-six".