45781 has 4 divisors (see below), whose sum is σ = 48492. Its totient is φ = 43072.

The previous prime is 45779. The next prime is 45817. The reversal of 45781 is 18754.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18754 = 2 ⋅9377.

It can be written as a sum of positive squares in 2 ways, for example, as 27556 + 18225 = 166^2 + 135^2 .

It is a cyclic number.

It is not a de Polignac number, because 45781 - 2¹ = 45779 is a prime.

It is a super-2 number, since 2×45781² = 4191799922, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (45751) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1330 + ... + 1363.

It is an arithmetic number, because the mean of its divisors is an integer number (12123).

2⁴⁵⁷⁸¹ is an apocalyptic number.

It is an amenable number.

45781 is a deficient number, since it is larger than the sum of its proper divisors (2711).

45781 is a wasteful number, since it uses less digits than its factorization.

45781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2710.

The product of its digits is 1120, while the sum is 25.

The square root of 45781 is about 213.9649504008. The cubic root of 45781 is about 35.7735268223.

The spelling of 45781 in words is "forty-five thousand, seven hundred eighty-one".