21804679 has 4 divisors (see below), whose sum is σ = 23481976. Its totient is φ = 20127384.

The previous prime is 21804641. The next prime is 21804683. The reversal of 21804679 is 97640812.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21804679 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21804179) 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 3 ways as a sum of consecutive naturals, for example, 838629 + ... + 838654.

It is an arithmetic number, because the mean of its divisors is an integer number (5870494).

Almost surely, 2^21804679 is an apocalyptic number.

21804679 is a deficient number, since it is larger than the sum of its proper divisors (1677297).

21804679 is a wasteful number, since it uses less digits than its factorization.

21804679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1677296.

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 21804679 is about 4669.5480509360. The cubic root of 21804679 is about 279.3722287677.

It can be divided in two parts, 2180 and 4679, that added together give a cube (6859 = 19³).

The spelling of 21804679 in words is "twenty-one million, eight hundred four thousand, six hundred seventy-nine".