21016841 has 4 divisors (see below), whose sum is σ = 21220992. Its totient is φ = 20812692.

The previous prime is 21016837. The next prime is 21016859. The reversal of 21016841 is 14861012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21016841 - 2² = 21016837 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21016241) 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, 101921 + ... + 102126.

It is an arithmetic number, because the mean of its divisors is an integer number (5305248).

Almost surely, 2^21016841 is an apocalyptic number.

It is an amenable number.

21016841 is a deficient number, since it is larger than the sum of its proper divisors (204151).

21016841 is a wasteful number, since it uses less digits than its factorization.

21016841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204150.

The product of its (nonzero) digits is 384, while the sum is 23.

The square root of 21016841 is about 4584.4128304506. The cubic root of 21016841 is about 275.9661487924.

Adding to 21016841 its reverse (14861012), we get a palindrome (35877853).

The spelling of 21016841 in words is "twenty-one million, sixteen thousand, eight hundred forty-one".