2106781 has 2 divisors, whose sum is σ = 2106782. Its totient is φ = 2106780.

The previous prime is 2106779. The next prime is 2106809. The reversal of 2106781 is 1876012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1368900 + 737881 = 1170^2 + 859^2 .

It is a cyclic number.

It is not a de Polignac number, because 2106781 - 2¹ = 2106779 is a prime.

It is a super-2 number, since 2×2106781² = 8877052363922, which contains 22 as substring.

Together with 2106779, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2106281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1053390 + 1053391.

It is an arithmetic number, because the mean of its divisors is an integer number (1053391).

2^2106781 is an apocalyptic number.

It is an amenable number.

2106781 is a deficient number, since it is larger than the sum of its proper divisors (1).

2106781 is an equidigital number, since it uses as much as digits as its factorization.

2106781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 672, while the sum is 25.

The square root of 2106781 is about 1451.4754562169. The cubic root of 2106781 is about 128.1956034425.

The spelling of 2106781 in words is "two million, one hundred six thousand, seven hundred eighty-one".