21810169 has 2 divisors, whose sum is σ = 21810170. Its totient is φ = 21810168.

The previous prime is 21810163. The next prime is 21810179. The reversal of 21810169 is 96101812.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20358144 + 1452025 = 4512^2 + 1205^2 .

It is a cyclic number.

It is not a de Polignac number, because 21810169 - 2¹¹ = 21808121 is a prime.

It is a super-2 number, since 2×21810169² = 951366943617122, which contains 22 as substring.

It is a Chen prime.

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

It is not a weakly prime, because it can be changed into another prime (21810163) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10905084 + 10905085.

It is an arithmetic number, because the mean of its divisors is an integer number (10905085).

Almost surely, 2^21810169 is an apocalyptic number.

It is an amenable number.

21810169 is a deficient number, since it is larger than the sum of its proper divisors (1).

21810169 is an equidigital number, since it uses as much as digits as its factorization.

21810169 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 28.

The square root of 21810169 is about 4670.1358652613. The cubic root of 21810169 is about 279.3956736566.

The spelling of 21810169 in words is "twenty-one million, eight hundred ten thousand, one hundred sixty-nine".