55781856 has 144 divisors (see below), whose sum is σ = 175017024. Its totient is φ = 16745472.

The previous prime is 55781849. The next prime is 55781857. The reversal of 55781856 is 65818755.

It is a tau number, because it is divible by the number of its divisors (144).

It is a super-2 number, since 2×55781856² = 6223230917609472, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55781857) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 175810 + ... + 176126.

It is an arithmetic number, because the mean of its divisors is an integer number (1215396).

Almost surely, 2^55781856 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 55781856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87508512).

55781856 is an abundant number, since it is smaller than the sum of its proper divisors (119235168).

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

55781856 is a wasteful number, since it uses less digits than its factorization.

55781856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 393 (or 382 counting only the distinct ones).

The product of its digits is 336000, while the sum is 45.

The square root of 55781856 is about 7468.7251924274. The cubic root of 55781856 is about 382.0888109800.

The spelling of 55781856 in words is "fifty-five million, seven hundred eighty-one thousand, eight hundred fifty-six".