55851221 has 4 divisors (see below), whose sum is σ = 55882944. Its totient is φ = 55819500.

The previous prime is 55851209. The next prime is 55851247. The reversal of 55851221 is 12215855.

55851221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 55851221 - 2⁶ = 55851157 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55851121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13055 + ... + 16796.

It is an arithmetic number, because the mean of its divisors is an integer number (13970736).

Almost surely, 2^55851221 is an apocalyptic number.

It is an amenable number.

55851221 is a deficient number, since it is larger than the sum of its proper divisors (31723).

55851221 is a wasteful number, since it uses less digits than its factorization.

55851221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31722.

The product of its digits is 4000, while the sum is 29.

The square root of 55851221 is about 7473.3674471419. The cubic root of 55851221 is about 382.2471217886.

The spelling of 55851221 in words is "fifty-five million, eight hundred fifty-one thousand, two hundred twenty-one".