21636145445621 has 4 divisors (see below), whose sum is σ = 24727023366432. Its totient is φ = 18545267524812.

The previous prime is 21636145445597. The next prime is 21636145445639. The reversal of 21636145445621 is 12654454163612.

It is a happy number.

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 not a de Polignac number, because 21636145445621 - 2⁶ = 21636145445557 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21636145445621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21636145445021) 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, 1545438960395 + ... + 1545438960408.

It is an arithmetic number, because the mean of its divisors is an integer number (6181755841608).

Almost surely, 2^{21636145445621} is an apocalyptic number.

It is an amenable number.

21636145445621 is a deficient number, since it is larger than the sum of its proper divisors (3090877920811).

21636145445621 is an equidigital number, since it uses as much as digits as its factorization.

21636145445621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3090877920810.

The product of its digits is 4147200, while the sum is 50.

The spelling of 21636145445621 in words is "twenty-one trillion, six hundred thirty-six billion, one hundred forty-five million, four hundred forty-five thousand, six hundred twenty-one".