55011221 has 4 divisors (see below), whose sum is σ = 55832352. Its totient is φ = 54190092.

The previous prime is 55011181. The next prime is 55011227. The reversal of 55011221 is 12211055.

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 55011221 - 2⁶ = 55011157 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 55011221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55011227) 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, 410465 + ... + 410598.

It is an arithmetic number, because the mean of its divisors is an integer number (13958088).

Almost surely, 2^55011221 is an apocalyptic number.

It is an amenable number.

55011221 is a deficient number, since it is larger than the sum of its proper divisors (821131).

55011221 is an equidigital number, since it uses as much as digits as its factorization.

55011221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 821130.

The product of its (nonzero) digits is 100, while the sum is 17.

The square root of 55011221 is about 7416.9549681793. The cubic root of 55011221 is about 380.3211066991.

Adding to 55011221 its reverse (12211055), we get a palindrome (67222276).

The spelling of 55011221 in words is "fifty-five million, eleven thousand, two hundred twenty-one".