21195608216837 has 4 divisors (see below), whose sum is σ = 21195618887436. Its totient is φ = 21195597546240.

The previous prime is 21195608216791. The next prime is 21195608216891. The reversal of 21195608216837 is 73861280659112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 21076904539681 + 118703677156 = 4590959^2 + 344534^2 .

It is a cyclic number.

It is not a de Polignac number, because 21195608216837 - 2⁸ = 21195608216581 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 (21195608219837) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1376738 + ... + 6654819.

It is an arithmetic number, because the mean of its divisors is an integer number (5298904721859).

Almost surely, 2^{21195608216837} is an apocalyptic number.

It is an amenable number.

21195608216837 is a deficient number, since it is larger than the sum of its proper divisors (10670599).

21195608216837 is an equidigital number, since it uses as much as digits as its factorization.

21195608216837 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10670598.

The product of its (nonzero) digits is 8709120, while the sum is 59.

The spelling of 21195608216837 in words is "twenty-one trillion, one hundred ninety-five billion, six hundred eight million, two hundred sixteen thousand, eight hundred thirty-seven".