21056605345 has 8 divisors (see below), whose sum is σ = 25268755176. Its totient is φ = 16844731776.

The previous prime is 21056605333. The next prime is 21056605417. The reversal of 21056605345 is 54350665012.

It can be written as a sum of positive squares in 4 ways, for example, as 3904250256 + 17152355089 = 62484^2 + 130967^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21056605345 - 2¹¹ = 21056603297 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 180819 + ... + 273511.

It is an arithmetic number, because the mean of its divisors is an integer number (3158594397).

Almost surely, 2^21056605345 is an apocalyptic number.

It is an amenable number.

21056605345 is a deficient number, since it is larger than the sum of its proper divisors (4212149831).

21056605345 is an equidigital number, since it uses as much as digits as its factorization.

21056605345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138131.

The product of its (nonzero) digits is 108000, while the sum is 37.

The spelling of 21056605345 in words is "twenty-one billion, fifty-six million, six hundred five thousand, three hundred forty-five".