55224721 has 6 divisors (see below), whose sum is σ = 58664630. Its totient is φ = 51975936.

The previous prime is 55224709. The next prime is 55224727. The reversal of 55224721 is 12742255.

It can be written as a sum of positive squares in 3 ways, for example, as 36180225 + 19044496 = 6015^2 + 4364^2 .

It is not a de Polignac number, because 55224721 - 2⁹ = 55224209 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 55224721.

It is not an unprimeable number, because it can be changed into a prime (55224727) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 95256 + ... + 95833.

Almost surely, 2^55224721 is an apocalyptic number.

It is an amenable number.

55224721 is a deficient number, since it is larger than the sum of its proper divisors (3439909).

55224721 is a wasteful number, since it uses less digits than its factorization.

55224721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 191123 (or 191106 counting only the distinct ones).

The product of its digits is 5600, while the sum is 28.

The square root of 55224721 is about 7431.3337295535. Note that the first 3 decimals coincide. The cubic root of 55224721 is about 380.8124836469.

Adding to 55224721 its reverse (12742255), we get a palindrome (67966976).

It can be divided in two parts, 55224 and 721, that added together give a triangular number (55945 = T₃₃₄).

The spelling of 55224721 in words is "fifty-five million, two hundred twenty-four thousand, seven hundred twenty-one".