20121617 has 4 divisors (see below), whose sum is σ = 20132160. Its totient is φ = 20111076.

The previous prime is 20121581. The next prime is 20121623. The reversal of 20121617 is 71612102.

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.

It is a cyclic number.

It is not a de Polignac number, because 20121617 - 2²⁴ = 3344401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20121667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1517 + ... + 6522.

It is an arithmetic number, because the mean of its divisors is an integer number (5033040).

Almost surely, 2^20121617 is an apocalyptic number.

It is an amenable number.

20121617 is a deficient number, since it is larger than the sum of its proper divisors (10543).

20121617 is an equidigital number, since it uses as much as digits as its factorization.

20121617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10542.

The product of its (nonzero) digits is 168, while the sum is 20.

The square root of 20121617 is about 4485.7125409460. The cubic root of 20121617 is about 271.9908490650.

Adding to 20121617 its reverse (71612102), we get a palindrome (91733719).

The spelling of 20121617 in words is "twenty million, one hundred twenty-one thousand, six hundred seventeen".