55031220 has 72 divisors (see below), whose sum is σ = 175724640. Its totient is φ = 13901760.

The previous prime is 55031191. The next prime is 55031237. The reversal of 55031220 is 2213055.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 55031193 and 55031202.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4626 + ... + 11465.

It is an arithmetic number, because the mean of its divisors is an integer number (2440620).

Almost surely, 2^55031220 is an apocalyptic number.

It is an amenable number.

55031220 is an abundant number, since it is smaller than the sum of its proper divisors (120693420).

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

55031220 is a wasteful number, since it uses less digits than its factorization.

55031220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16125 (or 16120 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 18.

The square root of 55031220 is about 7418.3030404534. The cubic root of 55031220 is about 380.3671889356.

Adding to 55031220 its reverse (2213055), we get a palindrome (57244275).

The spelling of 55031220 in words is "fifty-five million, thirty-one thousand, two hundred twenty".