2161978 has 24 divisors (see below), whose sum is σ = 4065012. Its totient is φ = 854784.

The previous prime is 2161967. The next prime is 2161987. The reversal of 2161978 is 8791612.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 2140369 + 21609 = 1463^2 + 147^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 426 + ... + 2122.

2^2161978 is an apocalyptic number.

2161978 is a deficient number, since it is larger than the sum of its proper divisors (1903034).

2161978 is a wasteful number, since it uses less digits than its factorization.

2161978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1726 (or 1719 counting only the distinct ones).

The product of its digits is 6048, while the sum is 34.

The square root of 2161978 is about 1470.3666209487. The cubic root of 2161978 is about 129.3055274360.

The spelling of 2161978 in words is "two million, one hundred sixty-one thousand, nine hundred seventy-eight".