57781 has 2 divisors, whose sum is σ = 57782. Its totient is φ = 57780.

The previous prime is 57773. The next prime is 57787. The reversal of 57781 is 18775.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 54756 + 3025 = 234^2 + 55^2 .

It is a cyclic number.

It is not a de Polignac number, because 57781 - 2³ = 57773 is a prime.

It is a super-2 number, since 2×57781² = 6677287922, which contains 22 as substring.

It is a nialpdrome in base 5.

It is a zygodrome in base 5.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (57787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28890 + 28891.

It is an arithmetic number, because the mean of its divisors is an integer number (28891).

2⁵⁷⁷⁸¹ is an apocalyptic number.

57781 is the 108-th centered decagonal number.

It is an amenable number.

57781 is a deficient number, since it is larger than the sum of its proper divisors (1).

57781 is an equidigital number, since it uses as much as digits as its factorization.

57781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1960, while the sum is 28.

The square root of 57781 is about 240.3767875649. The cubic root of 57781 is about 38.6599853035.

It can be divided in two parts, 57 and 781, that added together give a palindrome (838).

The spelling of 57781 in words is "fifty-seven thousand, seven hundred eighty-one".