2181656 has 32 divisors (see below), whose sum is σ = 4454400. Its totient is φ = 997920.

The previous prime is 2181649. The next prime is 2181659. The reversal of 2181656 is 6561812.

It is a happy number.

It is a hoax number, since the sum of its digits (29) coincides with the sum of the digits of its distinct prime factors.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2181659) 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, 4481 + ... + 4943.

It is an arithmetic number, because the mean of its divisors is an integer number (139200).

2^2181656 is an apocalyptic number.

It is an amenable number.

2181656 is an abundant number, since it is smaller than the sum of its proper divisors (2272744).

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

2181656 is a wasteful number, since it uses less digits than its factorization.

2181656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 519 (or 515 counting only the distinct ones).

The product of its digits is 2880, while the sum is 29.

The square root of 2181656 is about 1477.0429919268. The cubic root of 2181656 is about 129.6966496956.

The spelling of 2181656 in words is "two million, one hundred eighty-one thousand, six hundred fifty-six".