21653622336505 has 4 divisors (see below), whose sum is σ = 25984346803812. Its totient is φ = 17322897869200.

The previous prime is 21653622336499. The next prime is 21653622336517. The reversal of 21653622336505 is 50563322635612.

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 7090461235264 + 14563161101241 = 2662792^2 + 3816171^2 .

It is not a de Polignac number, because 21653622336505 - 2¹¹ = 21653622334457 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian 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, 2165362233646 + ... + 2165362233655.

It is an arithmetic number, because the mean of its divisors is an integer number (6496086700953).

Almost surely, 2^{21653622336505} is an apocalyptic number.

It is an amenable number.

21653622336505 is a deficient number, since it is larger than the sum of its proper divisors (4330724467307).

21653622336505 is an equidigital number, since it uses as much as digits as its factorization.

21653622336505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4330724467306.

The product of its (nonzero) digits is 5832000, while the sum is 49.

The spelling of 21653622336505 in words is "twenty-one trillion, six hundred fifty-three billion, six hundred twenty-two million, three hundred thirty-six thousand, five hundred five".