2163781 has 4 divisors (see below), whose sum is σ = 2167200. Its totient is φ = 2160364.

The previous prime is 2163767. The next prime is 2163787. The reversal of 2163781 is 1873612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2163781 - 2⁷ = 2163653 is a prime.

It is a super-2 number, since 2×2163781² = 9363896431922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2163787) 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, 451 + ... + 2128.

It is an arithmetic number, because the mean of its divisors is an integer number (541800).

2^2163781 is an apocalyptic number.

It is an amenable number.

2163781 is a deficient number, since it is larger than the sum of its proper divisors (3419).

2163781 is an equidigital number, since it uses as much as digits as its factorization.

2163781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3418.

The product of its digits is 2016, while the sum is 28.

The square root of 2163781 is about 1470.9796055690. The cubic root of 2163781 is about 129.3414625976.

The spelling of 2163781 in words is "two million, one hundred sixty-three thousand, seven hundred eighty-one".