21112187 has 4 divisors (see below), whose sum is σ = 21136080. Its totient is φ = 21088296.

The previous prime is 21112177. The next prime is 21112193. The reversal of 21112187 is 78121112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21112187 - 2⁸ = 21111931 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21112127) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10568 + ... + 12405.

It is an arithmetic number, because the mean of its divisors is an integer number (5284020).

Almost surely, 2^21112187 is an apocalyptic number.

21112187 is a deficient number, since it is larger than the sum of its proper divisors (23893).

21112187 is an equidigital number, since it uses as much as digits as its factorization.

21112187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23892.

The product of its digits is 224, while the sum is 23.

The square root of 21112187 is about 4594.7999956473. The cubic root of 21112187 is about 276.3828396829.

Adding to 21112187 its reverse (78121112), we get a palindrome (99233299).

The spelling of 21112187 in words is "twenty-one million, one hundred twelve thousand, one hundred eighty-seven".