21144187 has 2 divisors, whose sum is σ = 21144188. Its totient is φ = 21144186.

The previous prime is 21144181. The next prime is 21144203. The reversal of 21144187 is 78144112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21144187 - 2⁷ = 21144059 is a prime.

It is not a weakly prime, because it can be changed into another prime (21144181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10572093 + 10572094.

It is an arithmetic number, because the mean of its divisors is an integer number (10572094).

Almost surely, 2^21144187 is an apocalyptic number.

21144187 is a deficient number, since it is larger than the sum of its proper divisors (1).

21144187 is an equidigital number, since it uses as much as digits as its factorization.

21144187 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1792, while the sum is 28.

The square root of 21144187 is about 4598.2808744138. The cubic root of 21144187 is about 276.5224081414.

Adding to 21144187 its reverse (78144112), we get a palindrome (99288299).

The spelling of 21144187 in words is "twenty-one million, one hundred forty-four thousand, one hundred eighty-seven".