55311221 has 4 divisors (see below), whose sum is σ = 63212832. Its totient is φ = 47409612.

The previous prime is 55311211. The next prime is 55311227. The reversal of 55311221 is 12211355.

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 a de Polignac number, because none of the positive numbers 2^k-55311221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 55311193 and 55311202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55311227) 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, 3950795 + ... + 3950808.

It is an arithmetic number, because the mean of its divisors is an integer number (15803208).

Almost surely, 2^55311221 is an apocalyptic number.

It is an amenable number.

55311221 is a deficient number, since it is larger than the sum of its proper divisors (7901611).

55311221 is an equidigital number, since it uses as much as digits as its factorization.

55311221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7901610.

The product of its digits is 300, while the sum is 20.

The square root of 55311221 is about 7437.1514035953. The cubic root of 55311221 is about 381.0112056188.

Adding to 55311221 its reverse (12211355), we get a palindrome (67522576).

The spelling of 55311221 in words is "fifty-five million, three hundred eleven thousand, two hundred twenty-one".