13217521 has 4 divisors (see below), whose sum is σ = 13913200. Its totient is φ = 12521844.

The previous prime is 13217513. The next prime is 13217531. The reversal of 13217521 is 12571231.

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 a cyclic number.

It is not a de Polignac number, because 13217521 - 2³ = 13217513 is a prime.

It is a super-2 number, since 2×13217521² = 349405722770882, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 13217492 and 13217501.

It is not an unprimeable number, because it can be changed into a prime (13217531) 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, 347811 + ... + 347848.

It is an arithmetic number, because the mean of its divisors is an integer number (3478300).

Almost surely, 2^13217521 is an apocalyptic number.

It is an amenable number.

13217521 is a deficient number, since it is larger than the sum of its proper divisors (695679).

13217521 is an equidigital number, since it uses as much as digits as its factorization.

13217521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 695678.

The product of its digits is 420, while the sum is 22.

The square root of 13217521 is about 3635.5908735720. The cubic root of 13217521 is about 236.4376693455.

Adding to 13217521 its reverse (12571231), we get a palindrome (25788752).

The spelling of 13217521 in words is "thirteen million, two hundred seventeen thousand, five hundred twenty-one".