2161780 has 12 divisors (see below), whose sum is σ = 4539780. Its totient is φ = 864704.

The previous prime is 2161777. The next prime is 2161781. The reversal of 2161780 is 871612.

2161780 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 1004004 + 1157776 = 1002^2 + 1076^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2161781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 54025 + ... + 54064.

It is an arithmetic number, because the mean of its divisors is an integer number (378315).

2^2161780 is an apocalyptic number.

2161780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2161780 is an abundant number, since it is smaller than the sum of its proper divisors (2378000).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2161780 is a wasteful number, since it uses less digits than its factorization.

2161780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108098 (or 108096 counting only the distinct ones).

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

The square root of 2161780 is about 1470.2992892605. The cubic root of 2161780 is about 129.3015799280.

The spelling of 2161780 in words is "two million, one hundred sixty-one thousand, seven hundred eighty".