18307978 has 8 divisors (see below), whose sum is σ = 29574468. Its totient is φ = 8449824.

The previous prime is 18307937. The next prime is 18307979. The reversal of 18307978 is 87970381.

It can be written as a sum of positive squares in 2 ways, for example, as 15896169 + 2411809 = 3987^2 + 1553^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (18307979) 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 3 ways as a sum of consecutive naturals, for example, 352051 + ... + 352102.

Almost surely, 2^18307978 is an apocalyptic number.

18307978 is a deficient number, since it is larger than the sum of its proper divisors (11266490).

18307978 is a wasteful number, since it uses less digits than its factorization.

18307978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 704168.

The product of its (nonzero) digits is 84672, while the sum is 43.

The square root of 18307978 is about 4278.7823034130. The cubic root of 18307978 is about 263.5603813679.

The spelling of 18307978 in words is "eighteen million, three hundred seven thousand, nine hundred seventy-eight".