18499421 has 2 divisors, whose sum is σ = 18499422. Its totient is φ = 18499420.

The previous prime is 18499379. The next prime is 18499423. The reversal of 18499421 is 12499481.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18062500 + 436921 = 4250^2 + 661^2 .

It is an emirp because it is prime and its reverse (12499481) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18499421 - 2⁶ = 18499357 is a prime.

Together with 18499423, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18499423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9249710 + 9249711.

It is an arithmetic number, because the mean of its divisors is an integer number (9249711).

Almost surely, 2^18499421 is an apocalyptic number.

It is an amenable number.

18499421 is a deficient number, since it is larger than the sum of its proper divisors (1).

18499421 is an equidigital number, since it uses as much as digits as its factorization.

18499421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20736, while the sum is 38.

The square root of 18499421 is about 4301.0953256118. The cubic root of 18499421 is about 264.4758644506.

The spelling of 18499421 in words is "eighteen million, four hundred ninety-nine thousand, four hundred twenty-one".