21175719745 has 4 divisors (see below), whose sum is σ = 25410863700. Its totient is φ = 16940575792.

The previous prime is 21175719731. The next prime is 21175719749. The reversal of 21175719745 is 54791757112.

It is a happy number.

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 7924026289 + 13251693456 = 89017^2 + 115116^2 .

It is a cyclic number.

It is not a de Polignac number, because 21175719745 - 2⁹ = 21175719233 is a prime.

It is a super-2 number, since 2×21175719745² (a number of 21 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21175719749) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2117571970 + ... + 2117571979.

It is an arithmetic number, because the mean of its divisors is an integer number (6352715925).

Almost surely, 2^21175719745 is an apocalyptic number.

It is an amenable number.

21175719745 is a deficient number, since it is larger than the sum of its proper divisors (4235143955).

21175719745 is an equidigital number, since it uses as much as digits as its factorization.

21175719745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4235143954.

The product of its digits is 617400, while the sum is 49.

The spelling of 21175719745 in words is "twenty-one billion, one hundred seventy-five million, seven hundred nineteen thousand, seven hundred forty-five".