245781 has 8 divisors (see below), whose sum is σ = 364160. Its totient is φ = 163836.

The previous prime is 245771. The next prime is 245783. The reversal of 245781 is 187542.

It is not a de Polignac number, because 245781 - 2⁷ = 245653 is a prime.

It is a super-2 number, since 2×245781² = 120816599922, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 9103 = 245781 / (2 + 4 + 5 + 7 + 8 + 1).

It is a Duffinian number.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (245783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4525 + ... + 4578.

It is an arithmetic number, because the mean of its divisors is an integer number (45520).

2²⁴⁵⁷⁸¹ is an apocalyptic number.

It is an amenable number.

245781 is a deficient number, since it is larger than the sum of its proper divisors (118379).

245781 is an equidigital number, since it uses as much as digits as its factorization.

245781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9112 (or 9106 counting only the distinct ones).

The product of its digits is 2240, while the sum is 27.

The square root of 245781 is about 495.7630482398. The cubic root of 245781 is about 62.6396663273.

The spelling of 245781 in words is "two hundred forty-five thousand, seven hundred eighty-one".