20742517 has 2 divisors, whose sum is σ = 20742518. Its totient is φ = 20742516.

The previous prime is 20742493. The next prime is 20742521. The reversal of 20742517 is 71524702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19838116 + 904401 = 4454^2 + 951^2 .

It is a cyclic number.

It is not a de Polignac number, because 20742517 - 2¹¹ = 20740469 is a prime.

It is a super-2 number, since 2×20742517² = 860504022990578, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20742587) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10371258 + 10371259.

It is an arithmetic number, because the mean of its divisors is an integer number (10371259).

Almost surely, 2^20742517 is an apocalyptic number.

It is an amenable number.

20742517 is a deficient number, since it is larger than the sum of its proper divisors (1).

20742517 is an equidigital number, since it uses as much as digits as its factorization.

20742517 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3920, while the sum is 28.

The square root of 20742517 is about 4554.3953495497. The cubic root of 20742517 is about 274.7601964586.

It can be divided in two parts, 207 and 42517, that added together give a palindrome (42724).

The spelling of 20742517 in words is "twenty million, seven hundred forty-two thousand, five hundred seventeen".