2199978 has 48 divisors (see below), whose sum is σ = 5346432. Its totient is φ = 648000.

The previous prime is 2199971. The next prime is 2199979. The reversal of 2199978 is 8799912.

It is not an unprimeable number, because it can be changed into a prime (2199971) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7983 + ... + 8253.

It is an arithmetic number, because the mean of its divisors is an integer number (111384).

2^2199978 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2199978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2673216).

2199978 is an abundant number, since it is smaller than the sum of its proper divisors (3146454).

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

2199978 is a wasteful number, since it uses less digits than its factorization.

2199978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 331 (or 328 counting only the distinct ones).

The product of its digits is 81648, while the sum is 45.

The square root of 2199978 is about 1483.2322812021. The cubic root of 2199978 is about 130.0587111532.

Multiplying 2199978 by its reverse (8799912), we get a square (19359612801936 = 4399956²).

It can be divided in two parts, 21 and 99978, that added together give a palindrome (99999).

The spelling of 2199978 in words is "two million, one hundred ninety-nine thousand, nine hundred seventy-eight".