2121820 has 24 divisors (see below), whose sum is σ = 4483584. Its totient is φ = 843456.

The previous prime is 2121809. The next prime is 2121829. The reversal of 2121820 is 281212.

It is a super-2 number, since 2×2121820² = 9004240224800, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 2121794 and 2121803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121829) 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 7 ways as a sum of consecutive naturals, for example, 5349 + ... + 5731.

It is an arithmetic number, because the mean of its divisors is an integer number (186816).

2^2121820 is an apocalyptic number.

2121820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2121820 is an abundant number, since it is smaller than the sum of its proper divisors (2361764).

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

2121820 is a wasteful number, since it uses less digits than its factorization.

2121820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 669 (or 667 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

The square root of 2121820 is about 1456.6468343425. The cubic root of 2121820 is about 128.4999167284.

The spelling of 2121820 in words is "two million, one hundred twenty-one thousand, eight hundred twenty".