20605517 has 4 divisors (see below), whose sum is σ = 20616960. Its totient is φ = 20594076.

The previous prime is 20605477. The next prime is 20605531. The reversal of 20605517 is 71550602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 71550602 = 2 ⋅35775301.

It is a cyclic number.

It is not a de Polignac number, because 20605517 - 2¹² = 20601421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20605577) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2363 + ... + 6840.

It is an arithmetic number, because the mean of its divisors is an integer number (5154240).

Almost surely, 2^20605517 is an apocalyptic number.

It is an amenable number.

20605517 is a deficient number, since it is larger than the sum of its proper divisors (11443).

20605517 is an equidigital number, since it uses as much as digits as its factorization.

20605517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11442.

The product of its (nonzero) digits is 2100, while the sum is 26.

The square root of 20605517 is about 4539.3300166434. The cubic root of 20605517 is about 274.1539485092.

The spelling of 20605517 in words is "twenty million, six hundred five thousand, five hundred seventeen".