20917517 has 2 divisors, whose sum is σ = 20917518. Its totient is φ = 20917516.

The previous prime is 20917483. The next prime is 20917553. The reversal of 20917517 is 71571902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11095561 + 9821956 = 3331^2 + 3134^2 .

It is a cyclic number.

It is not a de Polignac number, because 20917517 - 2¹² = 20913421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20917597) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10458758 + 10458759.

It is an arithmetic number, because the mean of its divisors is an integer number (10458759).

Almost surely, 2^20917517 is an apocalyptic number.

It is an amenable number.

20917517 is a deficient number, since it is larger than the sum of its proper divisors (1).

20917517 is an equidigital number, since it uses as much as digits as its factorization.

20917517 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4410, while the sum is 32.

The square root of 20917517 is about 4573.5672073339. The cubic root of 20917517 is about 275.5307304410.

The spelling of 20917517 in words is "twenty million, nine hundred seventeen thousand, five hundred seventeen".