2121840 has 120 divisors (see below), whose sum is σ = 8163168. Its totient is φ = 483840.

The previous prime is 2121829. The next prime is 2121841. The reversal of 2121840 is 481212.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121841) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4830 + ... + 5250.

2^2121840 is an apocalyptic number.

2121840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2121840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4081584).

2121840 is an abundant number, since it is smaller than the sum of its proper divisors (6041328).

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

2121840 is a wasteful number, since it uses less digits than its factorization.

2121840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 447 (or 438 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 2121840 is about 1456.6536994083. The cubic root of 2121840 is about 128.5003204683.

The spelling of 2121840 in words is "two million, one hundred twenty-one thousand, eight hundred forty".