20529521 has 2 divisors, whose sum is σ = 20529522. Its totient is φ = 20529520.

The previous prime is 20529511. The next prime is 20529529. The reversal of 20529521 is 12592502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15689521 + 4840000 = 3961^2 + 2200^2 .

It is a cyclic number.

It is not a de Polignac number, because 20529521 - 2²² = 16335217 is a prime.

It is a super-2 number, since 2×20529521² = 842922464978882, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20529529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10264760 + 10264761.

It is an arithmetic number, because the mean of its divisors is an integer number (10264761).

Almost surely, 2^20529521 is an apocalyptic number.

It is an amenable number.

20529521 is a deficient number, since it is larger than the sum of its proper divisors (1).

20529521 is an equidigital number, since it uses as much as digits as its factorization.

20529521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 20529521 is about 4530.9514453368. The cubic root of 20529521 is about 273.8164940673.

The spelling of 20529521 in words is "twenty million, five hundred twenty-nine thousand, five hundred twenty-one".