55218420 has 144 divisors (see below), whose sum is σ = 175488768. Its totient is φ = 14042880.

The previous prime is 55218391. The next prime is 55218433. The reversal of 55218420 is 2481255.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 516007 + ... + 516113.

It is an arithmetic number, because the mean of its divisors is an integer number (1218672).

Almost surely, 2^55218420 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 55218420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87744384).

55218420 is an abundant number, since it is smaller than the sum of its proper divisors (120270348).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

55218420 is a wasteful number, since it uses less digits than its factorization.

55218420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230 (or 225 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 27.

The square root of 55218420 is about 7430.9097693351. The cubic root of 55218420 is about 380.7979998512.

Adding to 55218420 its reverse (2481255), we get a palindrome (57699675).

The spelling of 55218420 in words is "fifty-five million, two hundred eighteen thousand, four hundred twenty".