21361768613 has 4 divisors (see below), whose sum is σ = 21396279360. Its totient is φ = 21327257868.

The previous prime is 21361768607. The next prime is 21361768621. The reversal of 21361768613 is 31686716312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21361768613 - 2¹⁴ = 21361752229 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 (21361768313) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17254445 + ... + 17255682.

It is an arithmetic number, because the mean of its divisors is an integer number (5349069840).

Almost surely, 2^21361768613 is an apocalyptic number.

It is an amenable number.

21361768613 is a deficient number, since it is larger than the sum of its proper divisors (34510747).

21361768613 is an equidigital number, since it uses as much as digits as its factorization.

21361768613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34510746.

The product of its digits is 217728, while the sum is 44.

The spelling of 21361768613 in words is "twenty-one billion, three hundred sixty-one million, seven hundred sixty-eight thousand, six hundred thirteen".