2165978 has 4 divisors (see below), whose sum is σ = 3248970. Its totient is φ = 1082988.

The previous prime is 2165971. The next prime is 2166007. The reversal of 2165978 is 8795612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 1951609 + 214369 = 1397^2 + 463^2 .

It is not an unprimeable number, because it can be changed into a prime (2165971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 541493 + ... + 541496.

2^2165978 is an apocalyptic number.

2165978 is a deficient number, since it is larger than the sum of its proper divisors (1082992).

2165978 is a wasteful number, since it uses less digits than its factorization.

2165978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1082991.

The product of its digits is 30240, while the sum is 38.

The square root of 2165978 is about 1471.7261973615. The cubic root of 2165978 is about 129.3852235069.

The spelling of 2165978 in words is "two million, one hundred sixty-five thousand, nine hundred seventy-eight".