55820221 has 4 divisors (see below), whose sum is σ = 55875292. Its totient is φ = 55765152.

The previous prime is 55820207. The next prime is 55820227. The reversal of 55820221 is 12202855.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 53494596 + 2325625 = 7314^2 + 1525^2 .

It is a cyclic number.

It is not a de Polignac number, because 55820221 - 2¹⁷ = 55689149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55820227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25986 + ... + 28051.

It is an arithmetic number, because the mean of its divisors is an integer number (13968823).

Almost surely, 2^55820221 is an apocalyptic number.

It is an amenable number.

55820221 is a deficient number, since it is larger than the sum of its proper divisors (55071).

55820221 is a wasteful number, since it uses less digits than its factorization.

55820221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55070.

The product of its (nonzero) digits is 1600, while the sum is 25.

The square root of 55820221 is about 7471.2931276988. The cubic root of 55820221 is about 382.1763871140.

The spelling of 55820221 in words is "fifty-five million, eight hundred twenty thousand, two hundred twenty-one".