36781 has 2 divisors, whose sum is σ = 36782. Its totient is φ = 36780.

The previous prime is 36779. The next prime is 36787. The reversal of 36781 is 18763.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19881 + 16900 = 141^2 + 130^2 .

It is a cyclic number.

It is not a de Polignac number, because 36781 - 2¹ = 36779 is a prime.

It is a super-2 number, since 2×36781² = 2705683922, which contains 22 as substring.

Together with 36779, it forms a pair of twin primes.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (36787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 18390 + 18391.

It is an arithmetic number, because the mean of its divisors is an integer number (18391).

2³⁶⁷⁸¹ is an apocalyptic number.

It is an amenable number.

36781 is a deficient number, since it is larger than the sum of its proper divisors (1).

36781 is an equidigital number, since it uses as much as digits as its factorization.

36781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1008, while the sum is 25.

The square root of 36781 is about 191.7837323654. The cubic root of 36781 is about 33.2563445409.

The spelling of 36781 in words is "thirty-six thousand, seven hundred eighty-one".