20715517 has 2 divisors, whose sum is σ = 20715518. Its totient is φ = 20715516.

The previous prime is 20715493. The next prime is 20715547. The reversal of 20715517 is 71551702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18438436 + 2277081 = 4294^2 + 1509^2 .

It is a cyclic number.

It is not a de Polignac number, because 20715517 - 2¹⁵ = 20682749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20715547) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10357758 + 10357759.

It is an arithmetic number, because the mean of its divisors is an integer number (10357759).

Almost surely, 2^20715517 is an apocalyptic number.

It is an amenable number.

20715517 is a deficient number, since it is larger than the sum of its proper divisors (1).

20715517 is an equidigital number, since it uses as much as digits as its factorization.

20715517 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2450, while the sum is 28.

The square root of 20715517 is about 4551.4302147786. The cubic root of 20715517 is about 274.6409286046.

The spelling of 20715517 in words is "twenty million, seven hundred fifteen thousand, five hundred seventeen".