18888421 has 2 divisors, whose sum is σ = 18888422. Its totient is φ = 18888420.

The previous prime is 18888403. The next prime is 18888431. The reversal of 18888421 is 12488881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16900321 + 1988100 = 4111^2 + 1410^2 .

It is an emirp because it is prime and its reverse (12488881) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18888421 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18888431) 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, 9444210 + 9444211.

It is an arithmetic number, because the mean of its divisors is an integer number (9444211).

Almost surely, 2^18888421 is an apocalyptic number.

It is an amenable number.

18888421 is a deficient number, since it is larger than the sum of its proper divisors (1).

18888421 is an equidigital number, since it uses as much as digits as its factorization.

18888421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32768, while the sum is 40.

The square root of 18888421 is about 4346.0811083090. The cubic root of 18888421 is about 266.3167923710.

The spelling of 18888421 in words is "eighteen million, eight hundred eighty-eight thousand, four hundred twenty-one".