2001778 has 4 divisors (see below), whose sum is σ = 3002670. Its totient is φ = 1000888.

The previous prime is 2001751. The next prime is 2001787. The reversal of 2001778 is 8771002.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8771002 = 2 ⋅4385501.

It can be written as a sum of positive squares in only one way, i.e., 1734489 + 267289 = 1317^2 + 517^2 .

It is a super-2 number, since 2×2001778² = 8014230322568, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 500443 + ... + 500446.

2^2001778 is an apocalyptic number.

2001778 is a deficient number, since it is larger than the sum of its proper divisors (1000892).

2001778 is a wasteful number, since it uses less digits than its factorization.

2001778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1000891.

The product of its (nonzero) digits is 784, while the sum is 25.

The square root of 2001778 is about 1414.8420406533. The cubic root of 2001778 is about 126.0294295916.

The spelling of 2001778 in words is "two million, one thousand, seven hundred seventy-eight".