18920987 has 2 divisors, whose sum is σ = 18920988. Its totient is φ = 18920986.

The previous prime is 18920981. The next prime is 18921011. The reversal of 18920987 is 78902981.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18920987 - 2⁴ = 18920971 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18920981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9460493 + 9460494.

It is an arithmetic number, because the mean of its divisors is an integer number (9460494).

Almost surely, 2^18920987 is an apocalyptic number.

18920987 is a deficient number, since it is larger than the sum of its proper divisors (1).

18920987 is an equidigital number, since it uses as much as digits as its factorization.

18920987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72576, while the sum is 44.

The square root of 18920987 is about 4349.8260884776. The cubic root of 18920987 is about 266.4697589787.

The spelling of 18920987 in words is "eighteen million, nine hundred twenty thousand, nine hundred eighty-seven".