78315666 has 64 divisors (see below), whose sum is σ = 186109056. Its totient is φ = 21657600.

The previous prime is 78315661. The next prime is 78315673. The reversal of 78315666 is 66651387.

It is a super-2 number, since 2×78315666² = 12266687082047112, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78315661) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 82756 + ... + 83696.

It is an arithmetic number, because the mean of its divisors is an integer number (2907954).

Almost surely, 2^78315666 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 78315666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (93054528).

78315666 is an abundant number, since it is smaller than the sum of its proper divisors (107793390).

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

78315666 is a wasteful number, since it uses less digits than its factorization.

78315666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1067.

The product of its digits is 181440, while the sum is 42.

The square root of 78315666 is about 8849.6138898824. The cubic root of 78315666 is about 427.8414740306.

The spelling of 78315666 in words is "seventy-eight million, three hundred fifteen thousand, six hundred sixty-six".