21100117 has 4 divisors (see below), whose sum is σ = 21614796. Its totient is φ = 20585440.

The previous prime is 21100103. The next prime is 21100129. The reversal of 21100117 is 71100112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 2515396 + 18584721 = 1586^2 + 4311^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100117 - 2¹¹ = 21098069 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21100097 and 21100106.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 257278 + ... + 257359.

It is an arithmetic number, because the mean of its divisors is an integer number (5403699).

Almost surely, 2^21100117 is an apocalyptic number.

It is an amenable number.

21100117 is a deficient number, since it is larger than the sum of its proper divisors (514679).

21100117 is an equidigital number, since it uses as much as digits as its factorization.

21100117 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 514678.

The product of its (nonzero) digits is 14, while the sum is 13.

The square root of 21100117 is about 4593.4863665848. The cubic root of 21100117 is about 276.3301595760.

Adding to 21100117 its reverse (71100112), we get a palindrome (92200229).

The spelling of 21100117 in words is "twenty-one million, one hundred thousand, one hundred seventeen".