21198239 has 2 divisors, whose sum is σ = 21198240. Its totient is φ = 21198238.

The previous prime is 21198223. The next prime is 21198241. The reversal of 21198239 is 93289112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21198239 - 2⁴ = 21198223 is a prime.

It is a super-2 number, since 2×21198239² = 898730673402242, which contains 22 as substring.

Together with 21198241, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21198199 and 21198208.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21198139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10599119 + 10599120.

It is an arithmetic number, because the mean of its divisors is an integer number (10599120).

Almost surely, 2^21198239 is an apocalyptic number.

21198239 is a deficient number, since it is larger than the sum of its proper divisors (1).

21198239 is an equidigital number, since it uses as much as digits as its factorization.

21198239 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7776, while the sum is 35.

The square root of 21198239 is about 4604.1545369373. The cubic root of 21198239 is about 276.7578372455.

The spelling of 21198239 in words is "twenty-one million, one hundred ninety-eight thousand, two hundred thirty-nine".