21644218453 has 16 divisors (see below), whose sum is σ = 25447084992. Its totient is φ = 18149472000.

The previous prime is 21644218451. The next prime is 21644218537. The reversal of 21644218453 is 35481244612.

It is a happy number.

It is not a de Polignac number, because 21644218453 - 2¹ = 21644218451 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 (21644218451) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 139018 + ... + 250228.

It is an arithmetic number, because the mean of its divisors is an integer number (1590442812).

Almost surely, 2^21644218453 is an apocalyptic number.

It is an amenable number.

21644218453 is a deficient number, since it is larger than the sum of its proper divisors (3802866539).

21644218453 is a wasteful number, since it uses less digits than its factorization.

21644218453 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112596.

The product of its digits is 184320, while the sum is 40.

The spelling of 21644218453 in words is "twenty-one billion, six hundred forty-four million, two hundred eighteen thousand, four hundred fifty-three".