2121856 has 48 divisors (see below), whose sum is σ = 4680270. Its totient is φ = 957440.

The previous prime is 2121853. The next prime is 2121869. The reversal of 2121856 is 6581212.

2121856 = T₁₀₃ + T₁₀₄ + ... + T₂₃₉.

2121856 = 50² + 51² + ... + 186².

It can be written as a sum of positive squares in only one way, i.e., 1742400 + 379456 = 1320^2 + 616^2 .

It is an alternating number because its digits alternate between even and odd.

It is a self number, because there is not a number n which added to its sum of digits gives 2121856.

It is not an unprimeable number, because it can be changed into a prime (2121853) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 15420 + ... + 15556.

2^2121856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2121856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2340135).

2121856 is an abundant number, since it is smaller than the sum of its proper divisors (2558414).

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

2121856 is a wasteful number, since it uses less digits than its factorization.

2121856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173 (or 150 counting only the distinct ones).

The product of its digits is 960, while the sum is 25.

The square root of 2121856 is about 1456.6591914377. The cubic root of 2121856 is about 128.5006434585.

The spelling of 2121856 in words is "two million, one hundred twenty-one thousand, eight hundred fifty-six".