21652821363691 has 4 divisors (see below), whose sum is σ = 24746081558512. Its totient is φ = 18559561168872.

The previous prime is 21652821363673. The next prime is 21652821363697. The reversal of 21652821363691 is 19636312825612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21652821363691 - 2³⁷ = 21515382410219 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21652821363697) 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, 1546630097400 + ... + 1546630097413.

It is an arithmetic number, because the mean of its divisors is an integer number (6186520389628).

Almost surely, 2^{21652821363691} is an apocalyptic number.

21652821363691 is a deficient number, since it is larger than the sum of its proper divisors (3093260194821).

21652821363691 is an equidigital number, since it uses as much as digits as its factorization.

21652821363691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3093260194820.

The product of its digits is 5598720, while the sum is 55.

The spelling of 21652821363691 in words is "twenty-one trillion, six hundred fifty-two billion, eight hundred twenty-one million, three hundred sixty-three thousand, six hundred ninety-one".