21188887 has 2 divisors, whose sum is σ = 21188888. Its totient is φ = 21188886.

The previous prime is 21188803. The next prime is 21188897. The reversal of 21188887 is 78888112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21188887 - 2¹¹ = 21186839 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21188897) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10594443 + 10594444.

It is an arithmetic number, because the mean of its divisors is an integer number (10594444).

Almost surely, 2^21188887 is an apocalyptic number.

21188887 is a deficient number, since it is larger than the sum of its proper divisors (1).

21188887 is an equidigital number, since it uses as much as digits as its factorization.

21188887 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 57344, while the sum is 43.

The square root of 21188887 is about 4603.1388204137. The cubic root of 21188887 is about 276.7171322919.

It can be divided in two parts, 211 and 88887, that added together give a palindrome (89098).

The spelling of 21188887 in words is "twenty-one million, one hundred eighty-eight thousand, eight hundred eighty-seven".