20211517 has 2 divisors, whose sum is σ = 20211518. Its totient is φ = 20211516.

The previous prime is 20211493. The next prime is 20211523. The reversal of 20211517 is 71511202.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20169081 + 42436 = 4491^2 + 206^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20211517 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20211494 and 20211503.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20211617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10105758 + 10105759.

It is an arithmetic number, because the mean of its divisors is an integer number (10105759).

Almost surely, 2^20211517 is an apocalyptic number.

It is an amenable number.

20211517 is a deficient number, since it is larger than the sum of its proper divisors (1).

20211517 is an equidigital number, since it uses as much as digits as its factorization.

20211517 is an evil number, because the sum of its binary digits is even.

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

The square root of 20211517 is about 4495.7220777090. The cubic root of 20211517 is about 272.3953170836.

Adding to 20211517 its reverse (71511202), we get a palindrome (91722719).

The spelling of 20211517 in words is "twenty million, two hundred eleven thousand, five hundred seventeen".