55001220 has 48 divisors (see below), whose sum is σ = 154714560. Its totient is φ = 14599296.

The previous prime is 55001207. The next prime is 55001237. The reversal of 55001220 is 2210055.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 55001220.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11739 + ... + 15741.

It is an arithmetic number, because the mean of its divisors is an integer number (3223220).

Almost surely, 2^55001220 is an apocalyptic number.

It is an amenable number.

55001220 is an abundant number, since it is smaller than the sum of its proper divisors (99713340).

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

55001220 is a wasteful number, since it uses less digits than its factorization.

55001220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4244 (or 4242 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 15.

The square root of 55001220 is about 7416.2807390228. The cubic root of 55001220 is about 380.2980579353.

Adding to 55001220 its reverse (2210055), we get a palindrome (57211275).

The spelling of 55001220 in words is "fifty-five million, one thousand, two hundred twenty".