21644363720041 has 4 divisors (see below), whose sum is σ = 21645987344784. Its totient is φ = 21642740095300.

The previous prime is 21644363720039. The next prime is 21644363720051. The reversal of 21644363720041 is 14002736344612.

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 21644363720041 - 2¹ = 21644363720039 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 21644363720041.

It is not an unprimeable number, because it can be changed into a prime (21644363720051) 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, 811792375 + ... + 811819036.

It is an arithmetic number, because the mean of its divisors is an integer number (5411496836196).

Almost surely, 2^{21644363720041} is an apocalyptic number.

It is an amenable number.

21644363720041 is a deficient number, since it is larger than the sum of its proper divisors (1623624743).

21644363720041 is a wasteful number, since it uses less digits than its factorization.

21644363720041 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1623624742.

The product of its (nonzero) digits is 580608, while the sum is 43.

The spelling of 21644363720041 in words is "twenty-one trillion, six hundred forty-four billion, three hundred sixty-three million, seven hundred twenty thousand, forty-one".