21166529 has 2 divisors, whose sum is σ = 21166530. Its totient is φ = 21166528.

The previous prime is 21166517. The next prime is 21166559. The reversal of 21166529 is 92566112.

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., 16000000 + 5166529 = 4000^2 + 2273^2 .

It is a cyclic number.

It is not a de Polignac number, because 21166529 - 2¹⁶ = 21100993 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21166495 and 21166504.

It is not a weakly prime, because it can be changed into another prime (21166559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10583264 + 10583265.

It is an arithmetic number, because the mean of its divisors is an integer number (10583265).

Almost surely, 2^21166529 is an apocalyptic number.

It is an amenable number.

21166529 is a deficient number, since it is larger than the sum of its proper divisors (1).

21166529 is an equidigital number, since it uses as much as digits as its factorization.

21166529 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6480, while the sum is 32.

The square root of 21166529 is about 4600.7096191783. The cubic root of 21166529 is about 276.6197696353.

The spelling of 21166529 in words is "twenty-one million, one hundred sixty-six thousand, five hundred twenty-nine".