21100019 has 2 divisors, whose sum is σ = 21100020. Its totient is φ = 21100018.

The previous prime is 21100007. The next prime is 21100021. The reversal of 21100019 is 91000112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21100019 - 2⁴ = 21100003 is a prime.

It is a super-2 number, since 2×21100019² = 890421603600722, which contains 22 as substring.

Together with 21100021, 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 = 21099976 and 21100012.

It is not a weakly prime, because it can be changed into another prime (21100049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550009 + 10550010.

It is an arithmetic number, because the mean of its divisors is an integer number (10550010).

Almost surely, 2^21100019 is an apocalyptic number.

21100019 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100019 is an equidigital number, since it uses as much as digits as its factorization.

21100019 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18, while the sum is 14.

The square root of 21100019 is about 4593.4756992935. The cubic root of 21100019 is about 276.3297317680.

The spelling of 21100019 in words is "twenty-one million, one hundred thousand, nineteen".