21016911 has 4 divisors (see below), whose sum is σ = 28022552. Its totient is φ = 14011272.

The previous prime is 21016903. The next prime is 21016949. The reversal of 21016911 is 11961012.

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

It is not a de Polignac number, because 21016911 - 2³ = 21016903 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21016901) 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 in 3 ways as a sum of consecutive naturals, for example, 3502816 + ... + 3502821.

It is an arithmetic number, because the mean of its divisors is an integer number (7005638).

Almost surely, 2^21016911 is an apocalyptic number.

21016911 is a deficient number, since it is larger than the sum of its proper divisors (7005641).

21016911 is an equidigital number, since it uses as much as digits as its factorization.

21016911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7005640.

The product of its (nonzero) digits is 108, while the sum is 21.

The square root of 21016911 is about 4584.4204650097. The cubic root of 21016911 is about 275.9664551754.

Adding to 21016911 its reverse (11961012), we get a palindrome (32977923).

The spelling of 21016911 in words is "twenty-one million, sixteen thousand, nine hundred eleven".