65561221 has 8 divisors (see below), whose sum is σ = 72230688. Its totient is φ = 59010000.

The previous prime is 65561219. The next prime is 65561239. The reversal of 65561221 is 12216556.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 65561221 - 2¹ = 65561219 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 65561221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65561281) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28395 + ... + 30616.

It is an arithmetic number, because the mean of its divisors is an integer number (9028836).

Almost surely, 2^65561221 is an apocalyptic number.

It is an amenable number.

65561221 is a deficient number, since it is larger than the sum of its proper divisors (6669467).

65561221 is a wasteful number, since it uses less digits than its factorization.

65561221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59123.

The product of its digits is 3600, while the sum is 28.

The square root of 65561221 is about 8096.9883907537. The cubic root of 65561221 is about 403.2264488462.

Adding to 65561221 its reverse (12216556), we get a palindrome (77777777).

It can be divided in two parts, 6556 and 1221, that added together give a palindrome (7777).

The spelling of 65561221 in words is "sixty-five million, five hundred sixty-one thousand, two hundred twenty-one".