21106859 has 2 divisors, whose sum is σ = 21106860. Its totient is φ = 21106858.

The previous prime is 21106849. The next prime is 21106861. The reversal of 21106859 is 95860112.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21106859 is a prime.

It is a super-3 number, since 3×21106859³ (a number of 23 digits) contains 333 as substring.

It is a Sophie Germain prime.

Together with 21106861, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21106819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10553429 + 10553430.

It is an arithmetic number, because the mean of its divisors is an integer number (10553430).

Almost surely, 2^21106859 is an apocalyptic number.

21106859 is a deficient number, since it is larger than the sum of its proper divisors (1).

21106859 is an equidigital number, since it uses as much as digits as its factorization.

21106859 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 21106859 is about 4594.2201732176. The cubic root of 21106859 is about 276.3595878416.

The spelling of 21106859 in words is "twenty-one million, one hundred six thousand, eight hundred fifty-nine".