21105867 has 16 divisors (see below), whose sum is σ = 28933632. Its totient is φ = 13678560.

The previous prime is 21105863. The next prime is 21105907. The reversal of 21105867 is 76850112.

It is not a de Polignac number, because 21105867 - 2² = 21105863 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21105863) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25108 + ... + 25934.

It is an arithmetic number, because the mean of its divisors is an integer number (1808352).

Almost surely, 2^21105867 is an apocalyptic number.

21105867 is a deficient number, since it is larger than the sum of its proper divisors (7827765).

21105867 is a wasteful number, since it uses less digits than its factorization.

21105867 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1058.

The product of its (nonzero) digits is 3360, while the sum is 30.

The square root of 21105867 is about 4594.1122102099. The cubic root of 21105867 is about 276.3552582379.

Adding to 21105867 its reverse (76850112), we get a palindrome (97955979).

The spelling of 21105867 in words is "twenty-one million, one hundred five thousand, eight hundred sixty-seven".