2191644 has 96 divisors (see below), whose sum is σ = 7024640. Its totient is φ = 575424.

The previous prime is 2191633. The next prime is 2191687. The reversal of 2191644 is 4461912.

2191644 is a `hidden beast` number, since 2 + 19 + 1 + 644 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9717 + ... + 9939.

2^2191644 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 2191644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3512320).

2191644 is an abundant number, since it is smaller than the sum of its proper divisors (4832996).

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

2191644 is a wasteful number, since it uses less digits than its factorization.

2191644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 256 (or 248 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 2191644 is about 1480.4202106159. The cubic root of 2191644 is about 129.8942730115.

The spelling of 2191644 in words is "two million, one hundred ninety-one thousand, six hundred forty-four".