21678004 has 24 divisors (see below), whose sum is σ = 39529728. Its totient is φ = 10392480.

The previous prime is 21678001. The next prime is 21678037. The reversal of 21678004 is 40087612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21678001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9477 + ... + 11539.

It is an arithmetic number, because the mean of its divisors is an integer number (1647072).

Almost surely, 2^21678004 is an apocalyptic number.

It is an amenable number.

21678004 is a deficient number, since it is larger than the sum of its proper divisors (17851724).

21678004 is a wasteful number, since it uses less digits than its factorization.

21678004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2175 (or 2173 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 21678004 is about 4655.9643469425. The cubic root of 21678004 is about 278.8301703217.

The spelling of 21678004 in words is "twenty-one million, six hundred seventy-eight thousand, four".