2009781 has 12 divisors (see below), whose sum is σ = 2931552. Its totient is φ = 1326696.

The previous prime is 2009771. The next prime is 2009783. The reversal of 2009781 is 1879002.

It is a de Polignac number, because none of the positive numbers 2^k-2009781 is a prime.

It is a super-2 number, since 2×2009781² = 8078439335922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2009783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 81 + ... + 2006.

It is an arithmetic number, because the mean of its divisors is an integer number (244296).

2^2009781 is an apocalyptic number.

It is an amenable number.

2009781 is a deficient number, since it is larger than the sum of its proper divisors (921771).

2009781 is a wasteful number, since it uses less digits than its factorization.

2009781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2200 (or 2197 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 2009781 is about 1417.6674504269. The cubic root of 2009781 is about 126.1971592091.

The spelling of 2009781 in words is "two million, nine thousand, seven hundred eighty-one".