21682789 has 4 divisors (see below), whose sum is σ = 21692556. Its totient is φ = 21673024.

The previous prime is 21682757. The next prime is 21682823. The reversal of 21682789 is 98728612.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 16080100 + 5602689 = 4010^2 + 2367^2 .

It is a cyclic number.

It is not a de Polignac number, because 21682789 - 2⁵ = 21682757 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 (21682709) 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, 237 + ... + 6589.

It is an arithmetic number, because the mean of its divisors is an integer number (5423139).

Almost surely, 2^21682789 is an apocalyptic number.

It is an amenable number.

21682789 is a deficient number, since it is larger than the sum of its proper divisors (9767).

21682789 is an equidigital number, since it uses as much as digits as its factorization.

21682789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9766.

The product of its digits is 96768, while the sum is 43.

The square root of 21682789 is about 4656.4781756173. The cubic root of 21682789 is about 278.8506842677.

The spelling of 21682789 in words is "twenty-one million, six hundred eighty-two thousand, seven hundred eighty-nine".