2113821 has 6 divisors (see below), whose sum is σ = 3053310. Its totient is φ = 1409208.

The previous prime is 2113819. The next prime is 2113823. The reversal of 2113821 is 1283112.

It is an interprime number because it is at equal distance from previous prime (2113819) and next prime (2113823).

It can be written as a sum of positive squares in only one way, i.e., 1232100 + 881721 = 1110^2 + 939^2 .

It is not a de Polignac number, because 2113821 - 2¹ = 2113819 is a prime.

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 2113794 and 2113803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2113823) 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 5 ways as a sum of consecutive naturals, for example, 117426 + ... + 117443.

It is an arithmetic number, because the mean of its divisors is an integer number (508885).

2^2113821 is an apocalyptic number.

It is an amenable number.

2113821 is a deficient number, since it is larger than the sum of its proper divisors (939489).

2113821 is a wasteful number, since it uses less digits than its factorization.

2113821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 234875 (or 234872 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

The square root of 2113821 is about 1453.8985521693. The cubic root of 2113821 is about 128.3382371020.

Adding to 2113821 its reverse (1283112), we get a palindrome (3396933).

The spelling of 2113821 in words is "two million, one hundred thirteen thousand, eight hundred twenty-one".