55780 has 12 divisors (see below), whose sum is σ = 117180. Its totient is φ = 22304.

The previous prime is 55763. The next prime is 55787. The reversal of 55780 is 8755.

55780 = T₁₆₅ + T₁₆₆ + ... + T₁₆₈.

It can be written as a sum of positive squares in 2 ways, for example, as 27556 + 28224 = 166^2 + 168^2 .

It is a super-2 number, since 2×55780² = 6222816800, which contains 22 as substring.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (55787) by changing a digit.

55780 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1375 + ... + 1414.

It is an arithmetic number, because the mean of its divisors is an integer number (9765).

2⁵⁵⁷⁸⁰ is an apocalyptic number.

It is an amenable number.

55780 is an abundant number, since it is smaller than the sum of its proper divisors (61400).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (58590).

55780 is a wasteful number, since it uses less digits than its factorization.

55780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2798 (or 2796 counting only the distinct ones).

The product of its (nonzero) digits is 1400, while the sum is 25.

The square root of 55780 is about 236.1778990507. The cubic root of 55780 is about 38.2084573254.

Subtracting from 55780 its sum of digits (25), we obtain a palindrome (55755).

It can be divided in two parts, 5 and 5780, that multiplied together give a square (28900 = 170²).

The spelling of 55780 in words is "fifty-five thousand, seven hundred eighty".