7217521 has 4 divisors (see below), whose sum is σ = 7225072. Its totient is φ = 7209972.

The previous prime is 7217429. The next prime is 7217527. The reversal of 7217521 is 1257127.

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: 1257127 = 79 ⋅15913.

It is a cyclic number.

It is not a de Polignac number, because 7217521 - 2¹⁵ = 7184753 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7217527) 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, 2091 + ... + 4336.

It is an arithmetic number, because the mean of its divisors is an integer number (1806268).

Almost surely, 2^7217521 is an apocalyptic number.

It is an amenable number.

7217521 is a deficient number, since it is larger than the sum of its proper divisors (7551).

7217521 is a wasteful number, since it uses less digits than its factorization.

7217521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7550.

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

The square root of 7217521 is about 2686.5444347712. The cubic root of 7217521 is about 193.2543828120.

The spelling of 7217521 in words is "seven million, two hundred seventeen thousand, five hundred twenty-one".