21108587 has 2 divisors, whose sum is σ = 21108588. Its totient is φ = 21108586.

The previous prime is 21108557. The next prime is 21108631. The reversal of 21108587 is 78580112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21108587 - 2¹² = 21104491 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21108557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10554293 + 10554294.

It is an arithmetic number, because the mean of its divisors is an integer number (10554294).

Almost surely, 2^21108587 is an apocalyptic number.

21108587 is a deficient number, since it is larger than the sum of its proper divisors (1).

21108587 is an equidigital number, since it uses as much as digits as its factorization.

21108587 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4480, while the sum is 32.

The square root of 21108587 is about 4594.4082317530. The cubic root of 21108587 is about 276.3671294081.

Adding to 21108587 its reverse (78580112), we get a palindrome (99688699).

The spelling of 21108587 in words is "twenty-one million, one hundred eight thousand, five hundred eighty-seven".