21081169 has 2 divisors, whose sum is σ = 21081170. Its totient is φ = 21081168.

The previous prime is 21081161. The next prime is 21081187. The reversal of 21081169 is 96118012.

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., 20930625 + 150544 = 4575^2 + 388^2 .

It is a cyclic number.

It is not a de Polignac number, because 21081169 - 2³ = 21081161 is a prime.

It is a super-2 number, since 2×21081169² = 888831372813122, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21081161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10540584 + 10540585.

It is an arithmetic number, because the mean of its divisors is an integer number (10540585).

Almost surely, 2^21081169 is an apocalyptic number.

It is an amenable number.

21081169 is a deficient number, since it is larger than the sum of its proper divisors (1).

21081169 is an equidigital number, since it uses as much as digits as its factorization.

21081169 is an evil number, because the sum of its binary digits is even.

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

The square root of 21081169 is about 4591.4234176342. The cubic root of 21081169 is about 276.2474195619.

The spelling of 21081169 in words is "twenty-one million, eighty-one thousand, one hundred sixty-nine".