21678196 has 24 divisors (see below), whose sum is σ = 41557320. Its totient is φ = 9848832.

The previous prime is 21678161. The next prime is 21678197. The reversal of 21678196 is 69187612.

It can be written as a sum of positive squares in 4 ways, for example, as 2842596 + 18835600 = 1686^2 + 4340^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21678197) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3525 + ... + 7468.

It is an arithmetic number, because the mean of its divisors is an integer number (1731555).

Almost surely, 2^21678196 is an apocalyptic number.

It is an amenable number.

21678196 is a deficient number, since it is larger than the sum of its proper divisors (19879124).

21678196 is a wasteful number, since it uses less digits than its factorization.

21678196 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11043 (or 11041 counting only the distinct ones).

The product of its digits is 36288, while the sum is 40.

The square root of 21678196 is about 4655.9849656115. The cubic root of 21678196 is about 278.8309935100.

The spelling of 21678196 in words is "twenty-one million, six hundred seventy-eight thousand, one hundred ninety-six".