21175378117 has 4 divisors (see below), whose sum is σ = 21691850796. Its totient is φ = 20658905440.

The previous prime is 21175378097. The next prime is 21175378123. The reversal of 21175378117 is 71187357112.

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 848032641 + 20327345476 = 29121^2 + 142574^2 .

It is a cyclic number.

It is not a de Polignac number, because 21175378117 - 2⁷ = 21175377989 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 (21175378127) 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, 258236278 + ... + 258236359.

It is an arithmetic number, because the mean of its divisors is an integer number (5422962699).

Almost surely, 2^21175378117 is an apocalyptic number.

It is an amenable number.

21175378117 is a deficient number, since it is larger than the sum of its proper divisors (516472679).

21175378117 is an equidigital number, since it uses as much as digits as its factorization.

21175378117 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 516472678.

The product of its digits is 82320, while the sum is 43.

The spelling of 21175378117 in words is "twenty-one billion, one hundred seventy-five million, three hundred seventy-eight thousand, one hundred seventeen".