21109117 has 2 divisors, whose sum is σ = 21109118. Its totient is φ = 21109116.

The previous prime is 21109103. The next prime is 21109139. The reversal of 21109117 is 71190112.

It is an a-pointer prime, because the next prime (21109139) can be obtained adding 21109117 to its sum of digits (22).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10830681 + 10278436 = 3291^2 + 3206^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21109117 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21109177) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10554558 + 10554559.

It is an arithmetic number, because the mean of its divisors is an integer number (10554559).

Almost surely, 2^21109117 is an apocalyptic number.

It is an amenable number.

21109117 is a deficient number, since it is larger than the sum of its proper divisors (1).

21109117 is an equidigital number, since it uses as much as digits as its factorization.

21109117 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 126, while the sum is 22.

The square root of 21109117 is about 4594.4659102011. The cubic root of 21109117 is about 276.3694424217.

Adding to 21109117 its reverse (71190112), we get a palindrome (92299229).

It can be divided in two parts, 21109 and 117, that multiplied together give a triangular number (2469753 = T₂₂₂₂).

The spelling of 21109117 in words is "twenty-one million, one hundred nine thousand, one hundred seventeen".