20520517 has 2 divisors, whose sum is σ = 20520518. Its totient is φ = 20520516.

The previous prime is 20520509. The next prime is 20520523. The reversal of 20520517 is 71502502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20349121 + 171396 = 4511^2 + 414^2 .

It is a cyclic number.

It is not a de Polignac number, because 20520517 - 2³ = 20520509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20520527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10260258 + 10260259.

It is an arithmetic number, because the mean of its divisors is an integer number (10260259).

Almost surely, 2^20520517 is an apocalyptic number.

It is an amenable number.

20520517 is a deficient number, since it is larger than the sum of its proper divisors (1).

20520517 is an equidigital number, since it uses as much as digits as its factorization.

20520517 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 700, while the sum is 22.

The square root of 20520517 is about 4529.9577260721. The cubic root of 20520517 is about 273.7764573443.

The spelling of 20520517 in words is "twenty million, five hundred twenty thousand, five hundred seventeen".