21105789 has 32 divisors (see below), whose sum is σ = 32762880. Its totient is φ = 11987712.

The previous prime is 21105781. The next prime is 21105811. The reversal of 21105789 is 98750112.

It is not a de Polignac number, because 21105789 - 2³ = 21105781 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105781) 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 31 ways as a sum of consecutive naturals, for example, 21814 + ... + 22760.

It is an arithmetic number, because the mean of its divisors is an integer number (1023840).

Almost surely, 2^21105789 is an apocalyptic number.

It is an amenable number.

21105789 is a deficient number, since it is larger than the sum of its proper divisors (11657091).

21105789 is a wasteful number, since it uses less digits than its factorization.

21105789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1009.

The product of its (nonzero) digits is 5040, while the sum is 33.

The square root of 21105789 is about 4594.1037210755. The cubic root of 21105789 is about 276.3549177996.

The spelling of 21105789 in words is "twenty-one million, one hundred five thousand, seven hundred eighty-nine".