65531221 has 4 divisors (see below), whose sum is σ = 74892832. Its totient is φ = 56169612.

The previous prime is 65531203. The next prime is 65531261. The reversal of 65531221 is 12213556.

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 65531221 - 2⁷ = 65531093 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65531201) 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, 4680795 + ... + 4680808.

It is an arithmetic number, because the mean of its divisors is an integer number (18723208).

Almost surely, 2^65531221 is an apocalyptic number.

It is an amenable number.

65531221 is a deficient number, since it is larger than the sum of its proper divisors (9361611).

65531221 is an equidigital number, since it uses as much as digits as its factorization.

65531221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9361610.

The product of its digits is 1800, while the sum is 25.

The square root of 65531221 is about 8095.1356381471. The cubic root of 65531221 is about 403.1649356586.

Adding to 65531221 its reverse (12213556), we get a palindrome (77744777).

The spelling of 65531221 in words is "sixty-five million, five hundred thirty-one thousand, two hundred twenty-one".