55721808 has 60 divisors (see below), whose sum is σ = 159588000. Its totient is φ = 18139968.

The previous prime is 55721803. The next prime is 55721819. The reversal of 55721808 is 80812755.

55721808 is a `hidden beast` number, since 5 + 572 + 1 + 80 + 8 = 666.

55721808 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55721803) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 1693 + ... + 10691.

It is an arithmetic number, because the mean of its divisors is an integer number (2659800).

Almost surely, 2^55721808 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 55721808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (79794000).

55721808 is an abundant number, since it is smaller than the sum of its proper divisors (103866192).

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

55721808 is a wasteful number, since it uses less digits than its factorization.

55721808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9056 (or 9047 counting only the distinct ones).

The product of its (nonzero) digits is 22400, while the sum is 36.

The square root of 55721808 is about 7464.7041468500. The cubic root of 55721808 is about 381.9516582193.

The spelling of 55721808 in words is "fifty-five million, seven hundred twenty-one thousand, eight hundred eight".