40781 has 4 divisors (see below), whose sum is σ = 43932. Its totient is φ = 37632.

The previous prime is 40771. The next prime is 40787. The reversal of 40781 is 18704.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 27556 + 13225 = 166^2 + 115^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-40781 is a prime.

It is a super-2 number, since 2×40781² = 3326179922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 40781.

It is not an unprimeable number, because it can be changed into a prime (40787) 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, 1556 + ... + 1581.

It is an arithmetic number, because the mean of its divisors is an integer number (10983).

2⁴⁰⁷⁸¹ is an apocalyptic number.

It is an amenable number.

40781 is a deficient number, since it is larger than the sum of its proper divisors (3151).

40781 is a wasteful number, since it uses less digits than its factorization.

40781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3150.

The product of its (nonzero) digits is 224, while the sum is 20.

The square root of 40781 is about 201.9430612821. The cubic root of 40781 is about 34.4206676776.

The spelling of 40781 in words is "forty thousand, seven hundred eighty-one".