55121820 has 96 divisors (see below), whose sum is σ = 176033088. Its totient is φ = 12767232.

The previous prime is 55121819. The next prime is 55121849. The reversal of 55121820 is 2812155.

55121820 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×55121820² = 6076830080224800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 11182 + ... + 15338.

It is an arithmetic number, because the mean of its divisors is an integer number (1833678).

Almost surely, 2^55121820 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 55121820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88016544).

55121820 is an abundant number, since it is smaller than the sum of its proper divisors (120911268).

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

55121820 is a wasteful number, since it uses less digits than its factorization.

55121820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4199 (or 4197 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 24.

The square root of 55121820 is about 7424.4070470308. The cubic root of 55121820 is about 380.5758121678.

Adding to 55121820 its reverse (2812155), we get a palindrome (57933975).

The spelling of 55121820 in words is "fifty-five million, one hundred twenty-one thousand, eight hundred twenty".