163781 has 2 divisors, whose sum is σ = 163782. Its totient is φ = 163780.

The previous prime is 163771. The next prime is 163789. The reversal of 163781 is 187361.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 93025 + 70756 = 305^2 + 266^2 .

It is an emirp because it is prime and its reverse (187361) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 163781 - 2¹⁴ = 147397 is a prime.

It is a super-2 number, since 2×163781² = 53648431922, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 163781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (163789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 81890 + 81891.

It is an arithmetic number, because the mean of its divisors is an integer number (81891).

2¹⁶³⁷⁸¹ is an apocalyptic number.

It is an amenable number.

163781 is a deficient number, since it is larger than the sum of its proper divisors (1).

163781 is an equidigital number, since it uses as much as digits as its factorization.

163781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1008, while the sum is 26.

The square root of 163781 is about 404.6986533212. The cubic root of 163781 is about 54.7126612381.

The spelling of 163781 in words is "one hundred sixty-three thousand, seven hundred eighty-one".