2103781 has 2 divisors, whose sum is σ = 2103782. Its totient is φ = 2103780.

The previous prime is 2103769. The next prime is 2103791. The reversal of 2103781 is 1873012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1083681 + 1020100 = 1041^2 + 1010^2 .

It is a cyclic number.

It is not a de Polignac number, because 2103781 - 2⁵ = 2103749 is a prime.

It is a super-3 number, since 3×2103781³ = 27933338245821985623, which contains 333 as substring. Note that it is a super-d number also for d = 2.

2103781 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2103791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1051890 + 1051891.

It is an arithmetic number, because the mean of its divisors is an integer number (1051891).

2^2103781 is an apocalyptic number.

It is an amenable number.

2103781 is a deficient number, since it is larger than the sum of its proper divisors (1).

2103781 is an equidigital number, since it uses as much as digits as its factorization.

2103781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 2103781 is about 1450.4416568756. The cubic root of 2103781 is about 128.1347254961.

Adding to 2103781 its reverse (1873012), we get a palindrome (3976793).

The spelling of 2103781 in words is "two million, one hundred three thousand, seven hundred eighty-one".