21055246789 has 4 divisors (see below), whose sum is σ = 21106727020. Its totient is φ = 21003766560.

The previous prime is 21055246747. The next prime is 21055246837. The reversal of 21055246789 is 98764255012.

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 12727224225 + 8328022564 = 112815^2 + 91258^2 .

It is a cyclic number.

It is not a de Polignac number, because 21055246789 - 2²³ = 21046858181 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 (21055246189) 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, 25739502 + ... + 25740319.

It is an arithmetic number, because the mean of its divisors is an integer number (5276681755).

Almost surely, 2^21055246789 is an apocalyptic number.

It is an amenable number.

21055246789 is a deficient number, since it is larger than the sum of its proper divisors (51480231).

21055246789 is an equidigital number, since it uses as much as digits as its factorization.

21055246789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51480230.

The product of its (nonzero) digits is 1209600, while the sum is 49.

The spelling of 21055246789 in words is "twenty-one billion, fifty-five million, two hundred forty-six thousand, seven hundred eighty-nine".