21498109 has 2 divisors, whose sum is σ = 21498110. Its totient is φ = 21498108.

The previous prime is 21498107. The next prime is 21498121. The reversal of 21498109 is 90189412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21483225 + 14884 = 4635^2 + 122^2 .

It is a cyclic number.

It is not a de Polignac number, because 21498109 - 2¹ = 21498107 is a prime.

Together with 21498107, it forms a pair of twin primes.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21498107) 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, 10749054 + 10749055.

It is an arithmetic number, because the mean of its divisors is an integer number (10749055).

Almost surely, 2^21498109 is an apocalyptic number.

It is an amenable number.

21498109 is a deficient number, since it is larger than the sum of its proper divisors (1).

21498109 is an equidigital number, since it uses as much as digits as its factorization.

21498109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 21498109 is about 4636.6053314898. The cubic root of 21498109 is about 278.0567358281.

The spelling of 21498109 in words is "twenty-one million, four hundred ninety-eight thousand, one hundred nine".