21538219 has 2 divisors, whose sum is σ = 21538220. Its totient is φ = 21538218.

The previous prime is 21538169. The next prime is 21538261. The reversal of 21538219 is 91283512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21538219 - 2⁷ = 21538091 is a prime.

It is a super-2 number, since 2×21538219² = 927789755383922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21538519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10769109 + 10769110.

It is an arithmetic number, because the mean of its divisors is an integer number (10769110).

Almost surely, 2^21538219 is an apocalyptic number.

21538219 is a deficient number, since it is larger than the sum of its proper divisors (1).

21538219 is an equidigital number, since it uses as much as digits as its factorization.

21538219 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4320, while the sum is 31.

The square root of 21538219 is about 4640.9286786160. The cubic root of 21538219 is about 278.2295560937.

The spelling of 21538219 in words is "twenty-one million, five hundred thirty-eight thousand, two hundred nineteen".