2180781 has 6 divisors (see below), whose sum is σ = 3150030. Its totient is φ = 1453848.

The previous prime is 2180747. The next prime is 2180797. The reversal of 2180781 is 1870812.

It can be written as a sum of positive squares in only one way, i.e., 2160900 + 19881 = 1470^2 + 141^2 .

It is not a de Polignac number, because 2180781 - 2¹¹ = 2178733 is a prime.

It is a super-2 number, since 2×2180781² = 9511611539922, which contains 22 as substring.

It is a Curzon number.

2180781 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2180701) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 121146 + ... + 121163.

It is an arithmetic number, because the mean of its divisors is an integer number (525005).

2^2180781 is an apocalyptic number.

It is an amenable number.

2180781 is a deficient number, since it is larger than the sum of its proper divisors (969249).

2180781 is a wasteful number, since it uses less digits than its factorization.

2180781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 242315 (or 242312 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 27.

The square root of 2180781 is about 1476.7467623123. The cubic root of 2180781 is about 129.6793081679.

The spelling of 2180781 in words is "two million, one hundred eighty thousand, seven hundred eighty-one".