18383978 has 4 divisors (see below), whose sum is σ = 27575970. Its totient is φ = 9191988.

The previous prime is 18383977. The next prime is 18384007. The reversal of 18383978 is 87938381.

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., 13126129 + 5257849 = 3623^2 + 2293^2 .

It is not an unprimeable number, because it can be changed into a prime (18383971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4595993 + ... + 4595996.

Almost surely, 2^18383978 is an apocalyptic number.

18383978 is a deficient number, since it is larger than the sum of its proper divisors (9191992).

18383978 is an equidigital number, since it uses as much as digits as its factorization.

18383978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9191991.

The product of its digits is 290304, while the sum is 47.

The square root of 18383978 is about 4287.6541371710. The cubic root of 18383978 is about 263.9245747952.

It can be divided in two parts, 1838397 and 8, that multiplied together give a triangular number (14707176 = T₅₄₂₃).

The spelling of 18383978 in words is "eighteen million, three hundred eighty-three thousand, nine hundred seventy-eight".