55428821 has 4 divisors (see below), whose sum is σ = 63347232. Its totient is φ = 47510412.

The previous prime is 55428817. The next prime is 55428829. The reversal of 55428821 is 12882455.

It is a happy number.

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 55428821 - 2² = 55428817 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 (55428829) 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, 3959195 + ... + 3959208.

It is an arithmetic number, because the mean of its divisors is an integer number (15836808).

Almost surely, 2^55428821 is an apocalyptic number.

It is an amenable number.

55428821 is a deficient number, since it is larger than the sum of its proper divisors (7918411).

55428821 is an equidigital number, since it uses as much as digits as its factorization.

55428821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7918410.

The product of its digits is 25600, while the sum is 35.

The square root of 55428821 is about 7445.0534585052. The cubic root of 55428821 is about 381.2810435709.

The spelling of 55428821 in words is "fifty-five million, four hundred twenty-eight thousand, eight hundred twenty-one".