21306343165 has 4 divisors (see below), whose sum is σ = 25567611804. Its totient is φ = 17045074528.

The previous prime is 21306343147. The next prime is 21306343243. The reversal of 21306343165 is 56134360312.

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 2892395961 + 18413947204 = 53781^2 + 135698^2 .

It is a cyclic number.

It is not a de Polignac number, because 21306343165 - 2⁵ = 21306343133 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21306343165.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2130634312 + ... + 2130634321.

It is an arithmetic number, because the mean of its divisors is an integer number (6391902951).

Almost surely, 2^21306343165 is an apocalyptic number.

It is an amenable number.

21306343165 is a deficient number, since it is larger than the sum of its proper divisors (4261268639).

21306343165 is an equidigital number, since it uses as much as digits as its factorization.

21306343165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4261268638.

The product of its (nonzero) digits is 38880, while the sum is 34.

The spelling of 21306343165 in words is "twenty-one billion, three hundred six million, three hundred forty-three thousand, one hundred sixty-five".