20521001 has 2 divisors, whose sum is σ = 20521002. Its totient is φ = 20521000.

The previous prime is 20520971. The next prime is 20521013. The reversal of 20521001 is 10012502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20430400 + 90601 = 4520^2 + 301^2 .

It is a cyclic number.

It is not a de Polignac number, because 20521001 - 2⁶ = 20520937 is a prime.

It is a super-2 number, since 2×20521001² = 842222964084002, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20521301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10260500 + 10260501.

It is an arithmetic number, because the mean of its divisors is an integer number (10260501).

Almost surely, 2^20521001 is an apocalyptic number.

It is an amenable number.

20521001 is a deficient number, since it is larger than the sum of its proper divisors (1).

20521001 is an equidigital number, since it uses as much as digits as its factorization.

20521001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20, while the sum is 11.

The square root of 20521001 is about 4530.0111478892. The cubic root of 20521001 is about 273.7786097716.

Adding to 20521001 its reverse (10012502), we get a palindrome (30533503).

The spelling of 20521001 in words is "twenty million, five hundred twenty-one thousand, one".