20157217 has 4 divisors (see below), whose sum is σ = 20166336. Its totient is φ = 20148100.

The previous prime is 20157211. The next prime is 20157229. The reversal of 20157217 is 71275102.

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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 71275102 = 2 ⋅35637551.

It is a cyclic number.

It is not a de Polignac number, because 20157217 - 2³ = 20157209 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20157191 and 20157200.

It is not an unprimeable number, because it can be changed into a prime (20157211) 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, 1092 + ... + 6442.

It is an arithmetic number, because the mean of its divisors is an integer number (5041584).

Almost surely, 2^20157217 is an apocalyptic number.

It is an amenable number.

20157217 is a deficient number, since it is larger than the sum of its proper divisors (9119).

20157217 is an equidigital number, since it uses as much as digits as its factorization.

20157217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9118.

The product of its (nonzero) digits is 980, while the sum is 25.

The square root of 20157217 is about 4489.6789417507. The cubic root of 20157217 is about 272.1511603923.

The spelling of 20157217 in words is "twenty million, one hundred fifty-seven thousand, two hundred seventeen".