21016109 has 12 divisors (see below), whose sum is σ = 22878720. Its totient is φ = 19251000.

The previous prime is 21016103. The next prime is 21016123. The reversal of 21016109 is 90161012.

It is a de Polignac number, because none of the positive numbers 2^k-21016109 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21016103) 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 11 ways as a sum of consecutive naturals, for example, 17684 + ... + 18834.

It is an arithmetic number, because the mean of its divisors is an integer number (1906560).

Almost surely, 2^21016109 is an apocalyptic number.

It is an amenable number.

21016109 is a deficient number, since it is larger than the sum of its proper divisors (1862611).

21016109 is a wasteful number, since it uses less digits than its factorization.

21016109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1232 (or 1201 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 20.

The square root of 21016109 is about 4584.3329940134. The cubic root of 21016109 is about 275.9629448608.

The spelling of 21016109 in words is "twenty-one million, sixteen thousand, one hundred nine".