21606789 has 8 divisors (see below), whose sum is σ = 28933632. Its totient is φ = 14342240.

The previous prime is 21606787. The next prime is 21606817. The reversal of 21606789 is 98760612.

21606789 = 181² + 182² + ... + 413².

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21606789 - 2¹ = 21606787 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21606787) 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, 14757 + ... + 16154.

It is an arithmetic number, because the mean of its divisors is an integer number (3616704).

Almost surely, 2^21606789 is an apocalyptic number.

It is an amenable number.

21606789 is a deficient number, since it is larger than the sum of its proper divisors (7326843).

21606789 is a wasteful number, since it uses less digits than its factorization.

21606789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31147.

The product of its (nonzero) digits is 36288, while the sum is 39.

The square root of 21606789 is about 4648.3103381767. The cubic root of 21606789 is about 278.5245045036.

The spelling of 21606789 in words is "twenty-one million, six hundred six thousand, seven hundred eighty-nine".