2011978 has 4 divisors (see below), whose sum is σ = 3017970. Its totient is φ = 1005988.

The previous prime is 2011973. The next prime is 2011987. The reversal of 2011978 is 8791102.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8791102 = 2 ⋅4395551.

It can be written as a sum of positive squares in only one way, i.e., 1923769 + 88209 = 1387^2 + 297^2 .

It is not an unprimeable number, because it can be changed into a prime (2011973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 502993 + ... + 502996.

2^2011978 is an apocalyptic number.

2011978 is a deficient number, since it is larger than the sum of its proper divisors (1005992).

2011978 is a wasteful number, since it uses less digits than its factorization.

2011978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1005991.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 2011978 is about 1418.4421031540. The cubic root of 2011978 is about 126.2431267702.

The spelling of 2011978 in words is "two million, eleven thousand, nine hundred seventy-eight".