21755565994523 has 2 divisors, whose sum is σ = 21755565994524. Its totient is φ = 21755565994522.

The previous prime is 21755565994511. The next prime is 21755565994537. The reversal of 21755565994523 is 32549956555712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21755565994523 - 2⁴ = 21755565994507 is a prime.

It is not a weakly prime, because it can be changed into another prime (21755595994523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10877782997261 + 10877782997262.

It is an arithmetic number, because the mean of its divisors is an integer number (10877782997262).

Almost surely, 2^{21755565994523} is an apocalyptic number.

21755565994523 is a deficient number, since it is larger than the sum of its proper divisors (1).

21755565994523 is an equidigital number, since it uses as much as digits as its factorization.

21755565994523 is an evil number, because the sum of its binary digits is even.

The product of its digits is 510300000, while the sum is 68.

The spelling of 21755565994523 in words is "twenty-one trillion, seven hundred fifty-five billion, five hundred sixty-five million, nine hundred ninety-four thousand, five hundred twenty-three".