18857989 has 2 divisors, whose sum is σ = 18857990. Its totient is φ = 18857988.

The previous prime is 18857977. The next prime is 18858019. The reversal of 18857989 is 98975881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16402500 + 2455489 = 4050^2 + 1567^2 .

It is an emirp because it is prime and its reverse (98975881) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18857989 - 2⁹ = 18857477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18857929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9428994 + 9428995.

It is an arithmetic number, because the mean of its divisors is an integer number (9428995).

Almost surely, 2^18857989 is an apocalyptic number.

It is an amenable number.

18857989 is a deficient number, since it is larger than the sum of its proper divisors (1).

18857989 is an equidigital number, since it uses as much as digits as its factorization.

18857989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1451520, while the sum is 55.

The square root of 18857989 is about 4342.5786118388. The cubic root of 18857989 is about 266.1736904310.

The spelling of 18857989 in words is "eighteen million, eight hundred fifty-seven thousand, nine hundred eighty-nine".