10217721 has 4 divisors (see below), whose sum is σ = 13623632. Its totient is φ = 6811812.

The previous prime is 10217707. The next prime is 10217723. The reversal of 10217721 is 12771201.

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 an emirpimes, since its reverse is a distinct semiprime: 12771201 = 3 ⋅4257067.

It is not a de Polignac number, because 10217721 - 2¹⁰ = 10216697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (10217723) 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, 1702951 + ... + 1702956.

It is an arithmetic number, because the mean of its divisors is an integer number (3405908).

Almost surely, 2^10217721 is an apocalyptic number.

It is an amenable number.

10217721 is a deficient number, since it is larger than the sum of its proper divisors (3405911).

10217721 is an equidigital number, since it uses as much as digits as its factorization.

10217721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3405910.

The product of its (nonzero) digits is 196, while the sum is 21.

The square root of 10217721 is about 3196.5170107478. The cubic root of 10217721 is about 216.9958092730.

Adding to 10217721 its reverse (12771201), we get a palindrome (22988922).

The spelling of 10217721 in words is "ten million, two hundred seventeen thousand, seven hundred twenty-one".