2163861 has 24 divisors (see below), whose sum is σ = 3698240. Its totient is φ = 1224936.

The previous prime is 2163859. The next prime is 2163869. The reversal of 2163861 is 1683612.

2163861 is a `hidden beast` number, since 21 + 638 + 6 + 1 = 666.

It is not a de Polignac number, because 2163861 - 2¹ = 2163859 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

2163861 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2163869) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20170 + ... + 20276.

2^2163861 is an apocalyptic number.

2163861 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2163861 is a deficient number, since it is larger than the sum of its proper divisors (1534379).

2163861 is an equidigital number, since it uses as much as digits as its factorization.

2163861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 230 (or 117 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 2163861 is about 1471.0067980808. The cubic root of 2163861 is about 129.3430565959.

Subtracting from 2163861 its reverse (1683612), we obtain a square (480249 = 693²).

The spelling of 2163861 in words is "two million, one hundred sixty-three thousand, eight hundred sixty-one".