2085781 has 4 divisors (see below), whose sum is σ = 2208492. Its totient is φ = 1963072.

The previous prime is 2085779. The next prime is 2085799. The reversal of 2085781 is 1875802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1875802 = 2 ⋅937901.

It can be written as a sum of positive squares in 2 ways, for example, as 624100 + 1461681 = 790^2 + 1209^2 .

It is a cyclic number.

It is not a de Polignac number, because 2085781 - 2¹ = 2085779 is a prime.

It is a super-2 number, since 2×2085781² = 8700964759922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2085701) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 61330 + ... + 61363.

It is an arithmetic number, because the mean of its divisors is an integer number (552123).

2^2085781 is an apocalyptic number.

It is an amenable number.

2085781 is a deficient number, since it is larger than the sum of its proper divisors (122711).

2085781 is a wasteful number, since it uses less digits than its factorization.

2085781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122710.

The product of its (nonzero) digits is 4480, while the sum is 31.

The square root of 2085781 is about 1444.2233206814. The cubic root of 2085781 is about 127.7682370248.

The spelling of 2085781 in words is "two million, eighty-five thousand, seven hundred eighty-one".