21106187 has 2 divisors, whose sum is σ = 21106188. Its totient is φ = 21106186.

The previous prime is 21106181. The next prime is 21106199. The reversal of 21106187 is 78160112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21106187 - 2¹² = 21102091 is a prime.

It is a super-2 number, since 2×21106187² = 890942259357938, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21106181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10553093 + 10553094.

It is an arithmetic number, because the mean of its divisors is an integer number (10553094).

Almost surely, 2^21106187 is an apocalyptic number.

21106187 is a deficient number, since it is larger than the sum of its proper divisors (1).

21106187 is an equidigital number, since it uses as much as digits as its factorization.

21106187 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 672, while the sum is 26.

The square root of 21106187 is about 4594.1470372638. The cubic root of 21106187 is about 276.3566548991.

Adding to 21106187 its reverse (78160112), we get a palindrome (99266299).

The spelling of 21106187 in words is "twenty-one million, one hundred six thousand, one hundred eighty-seven".