2117851 has 4 divisors (see below), whose sum is σ = 2137752. Its totient is φ = 2097952.

The previous prime is 2117849. The next prime is 2117861. The reversal of 2117851 is 1587112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 2117851 - 2¹ = 2117849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2117821) 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, 9790 + ... + 10003.

It is an arithmetic number, because the mean of its divisors is an integer number (534438).

2^2117851 is an apocalyptic number.

2117851 is a deficient number, since it is larger than the sum of its proper divisors (19901).

2117851 is a wasteful number, since it uses less digits than its factorization.

2117851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19900.

The product of its digits is 560, while the sum is 25.

The square root of 2117851 is about 1455.2838211153. The cubic root of 2117851 is about 128.4197442811.

It can be divided in two parts, 211 and 7851, that multiplied together give a palindrome (1656561).

The spelling of 2117851 in words is "two million, one hundred seventeen thousand, eight hundred fifty-one".