18443987 has 2 divisors, whose sum is σ = 18443988. Its totient is φ = 18443986.

The previous prime is 18443969. The next prime is 18443993. The reversal of 18443987 is 78934481.

It is a strong prime.

It is an emirp because it is prime and its reverse (78934481) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18443987 - 2⁶ = 18443923 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18443587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9221993 + 9221994.

It is an arithmetic number, because the mean of its divisors is an integer number (9221994).

Almost surely, 2^18443987 is an apocalyptic number.

18443987 is a deficient number, since it is larger than the sum of its proper divisors (1).

18443987 is an equidigital number, since it uses as much as digits as its factorization.

18443987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 193536, while the sum is 44.

The square root of 18443987 is about 4294.6463183829. The cubic root of 18443987 is about 264.2114305263.

The spelling of 18443987 in words is "eighteen million, four hundred forty-three thousand, nine hundred eighty-seven".