2181996 has 18 divisors (see below), whose sum is σ = 5515692. Its totient is φ = 727320.

The previous prime is 2181973. The next prime is 2182007. The reversal of 2181996 is 6991812.

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-2 number, since 2×2181996² = 9522213088032, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 60611 = 2181996 / (2 + 1 + 8 + 1 + 9 + 9 + 6).

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 2181996.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 30270 + ... + 30341.

2^2181996 is an apocalyptic number.

It is an amenable number.

2181996 is an abundant number, since it is smaller than the sum of its proper divisors (3333696).

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

2181996 is a wasteful number, since it uses less digits than its factorization.

2181996 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60621 (or 60616 counting only the distinct ones).

The product of its digits is 7776, while the sum is 36.

The square root of 2181996 is about 1477.1580822647. The cubic root of 2181996 is about 129.7033868668.

The spelling of 2181996 in words is "two million, one hundred eighty-one thousand, nine hundred ninety-six".