19997517 has 4 divisors (see below), whose sum is σ = 26663360. Its totient is φ = 13331676.

The previous prime is 19997489. The next prime is 19997521. The reversal of 19997517 is 71579991.

It is a happy number.

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.

It is not a de Polignac number, because 19997517 - 2²² = 15803213 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 (19997567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3332917 + ... + 3332922.

It is an arithmetic number, because the mean of its divisors is an integer number (6665840).

Almost surely, 2^19997517 is an apocalyptic number.

It is an amenable number.

19997517 is a deficient number, since it is larger than the sum of its proper divisors (6665843).

19997517 is an equidigital number, since it uses as much as digits as its factorization.

19997517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6665842.

The product of its digits is 178605, while the sum is 48.

The square root of 19997517 is about 4471.8583385434. The cubic root of 19997517 is about 271.4305280297.

The spelling of 19997517 in words is "nineteen million, nine hundred ninety-seven thousand, five hundred seventeen".