21813925209443 has 16 divisors (see below), whose sum is σ = 22729293333600. Its totient is φ = 20909445580800.

The previous prime is 21813925209421. The next prime is 21813925209469. The reversal of 21813925209443 is 34490252931812.

It is a Cunningham number, because it is equal to 4670538²-1.

It is a cyclic number.

It is not a de Polignac number, because 21813925209443 - 2⁸ = 21813925209187 is a prime.

It is a Smith number, since the sum of its digits (53) 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 not an unprimeable number, because it can be changed into a prime (21813925209413) 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, 135365105 + ... + 135526157.

It is an arithmetic number, because the mean of its divisors is an integer number (1420580833350).

Almost surely, 2^{21813925209443} is an apocalyptic number.

21813925209443 is a deficient number, since it is larger than the sum of its proper divisors (915368124157).

21813925209443 is a wasteful number, since it uses less digits than its factorization.

21813925209443 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194822.

The product of its (nonzero) digits is 3732480, while the sum is 53.

The spelling of 21813925209443 in words is "twenty-one trillion, eight hundred thirteen billion, nine hundred twenty-five million, two hundred nine thousand, four hundred forty-three".