21606251526613 has 4 divisors (see below), whose sum is σ = 23268270874828. Its totient is φ = 19944232178400.

The previous prime is 21606251526611. The next prime is 21606251526641. The reversal of 21606251526613 is 31662515260612.

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 2372702768164 + 19233548758449 = 1540358^2 + 4385607^2 .

It is a cyclic number.

It is not a de Polignac number, because 21606251526613 - 2¹ = 21606251526611 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 (21606251526611) 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, 831009674088 + ... + 831009674113.

It is an arithmetic number, because the mean of its divisors is an integer number (5817067718707).

Almost surely, 2^{21606251526613} is an apocalyptic number.

It is an amenable number.

21606251526613 is a deficient number, since it is larger than the sum of its proper divisors (1662019348215).

21606251526613 is a wasteful number, since it uses less digits than its factorization.

21606251526613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1662019348214.

The product of its (nonzero) digits is 777600, while the sum is 46.

The spelling of 21606251526613 in words is "twenty-one trillion, six hundred six billion, two hundred fifty-one million, five hundred twenty-six thousand, six hundred thirteen".