55021121 has 4 divisors (see below), whose sum is σ = 55371732. Its totient is φ = 54670512.

The previous prime is 55021117. The next prime is 55021151. The reversal of 55021121 is 12112055.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12112055 = 5 ⋅2422411.

It can be written as a sum of positive squares in 2 ways, for example, as 19678096 + 35343025 = 4436^2 + 5945^2 .

It is a cyclic number.

It is not a de Polignac number, because 55021121 - 2² = 55021117 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 55021121.

It is not an unprimeable number, because it can be changed into a prime (55021111) 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, 175070 + ... + 175383.

It is an arithmetic number, because the mean of its divisors is an integer number (13842933).

Almost surely, 2^55021121 is an apocalyptic number.

It is an amenable number.

55021121 is a deficient number, since it is larger than the sum of its proper divisors (350611).

55021121 is a wasteful number, since it uses less digits than its factorization.

55021121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 350610.

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

The square root of 55021121 is about 7417.6223279431. The cubic root of 55021121 is about 380.3439199424.

Adding to 55021121 its reverse (12112055), we get a palindrome (67133176).

The spelling of 55021121 in words is "fifty-five million, twenty-one thousand, one hundred twenty-one".