20711521 has 2 divisors, whose sum is σ = 20711522. Its totient is φ = 20711520.

The previous prime is 20711497. The next prime is 20711531. The reversal of 20711521 is 12511702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12503296 + 8208225 = 3536^2 + 2865^2 .

It is a cyclic number.

It is not a de Polignac number, because 20711521 - 2¹¹ = 20709473 is a prime.

It is not a weakly prime, because it can be changed into another prime (20711531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10355760 + 10355761.

It is an arithmetic number, because the mean of its divisors is an integer number (10355761).

Almost surely, 2^20711521 is an apocalyptic number.

It is an amenable number.

20711521 is a deficient number, since it is larger than the sum of its proper divisors (1).

20711521 is an equidigital number, since it uses as much as digits as its factorization.

20711521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 140, while the sum is 19.

The square root of 20711521 is about 4550.9912107144. The cubic root of 20711521 is about 274.6232681600.

The spelling of 20711521 in words is "twenty million, seven hundred eleven thousand, five hundred twenty-one".