21105472789 has 4 divisors (see below), whose sum is σ = 21620240460. Its totient is φ = 20590705120.

The previous prime is 21105472781. The next prime is 21105472813. The reversal of 21105472789 is 98727450112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 12506619889 + 8598852900 = 111833^2 + 92730^2 .

It is not a de Polignac number, because 21105472789 - 2³ = 21105472781 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 (21105472781) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 257383774 + ... + 257383855.

It is an arithmetic number, because the mean of its divisors is an integer number (5405060115).

Almost surely, 2^21105472789 is an apocalyptic number.

It is an amenable number.

21105472789 is a deficient number, since it is larger than the sum of its proper divisors (514767671).

21105472789 is an equidigital number, since it uses as much as digits as its factorization.

21105472789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 514767670.

The product of its (nonzero) digits is 282240, while the sum is 46.

The spelling of 21105472789 in words is "twenty-one billion, one hundred five million, four hundred seventy-two thousand, seven hundred eighty-nine".