18313978 has 4 divisors (see below), whose sum is σ = 27470970. Its totient is φ = 9156988.

The previous prime is 18313961. The next prime is 18313979. The reversal of 18313978 is 87931381.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87931381 = 2459 ⋅35759.

It can be written as a sum of positive squares in only one way, i.e., 17833729 + 480249 = 4223^2 + 693^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 18313978.

It is not an unprimeable number, because it can be changed into a prime (18313979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4578493 + ... + 4578496.

Almost surely, 2^18313978 is an apocalyptic number.

18313978 is a deficient number, since it is larger than the sum of its proper divisors (9156992).

18313978 is an equidigital number, since it uses as much as digits as its factorization.

18313978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9156991.

The product of its digits is 36288, while the sum is 40.

The square root of 18313978 is about 4279.4833800355. The cubic root of 18313978 is about 263.5891700844.

It can be divided in two parts, 18313 and 978, that added together give a palindrome (19291).

The spelling of 18313978 in words is "eighteen million, three hundred thirteen thousand, nine hundred seventy-eight".