2001556 has 6 divisors (see below), whose sum is σ = 3502730. Its totient is φ = 1000776.

The previous prime is 2001553. The next prime is 2001581. The reversal of 2001556 is 6551002.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 1988100 + 13456 = 1410^2 + 116^2 .

It is a super-2 number, since 2×2001556² = 8012452842272, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2001553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 250191 + ... + 250198.

2^2001556 is an apocalyptic number.

It is an amenable number.

2001556 is a deficient number, since it is larger than the sum of its proper divisors (1501174).

2001556 is a wasteful number, since it uses less digits than its factorization.

2001556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 500393 (or 500391 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 2001556 is about 1414.7635844904. The cubic root of 2001556 is about 126.0247704723.

Adding to 2001556 its reverse (6551002), we get a palindrome (8552558).

The spelling of 2001556 in words is "two million, one thousand, five hundred fifty-six".