21563231634523 has 2 divisors, whose sum is σ = 21563231634524. Its totient is φ = 21563231634522.

The previous prime is 21563231634521. The next prime is 21563231634541. The reversal of 21563231634523 is 32543613236512.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21563231634523 - 2¹ = 21563231634521 is a prime.

It is a super-3 number, since 3×21563231634523³ (a number of 41 digits) contains 333 as substring.

Together with 21563231634521, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21563231634521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10781615817261 + 10781615817262.

It is an arithmetic number, because the mean of its divisors is an integer number (10781615817262).

Almost surely, 2^{21563231634523} is an apocalyptic number.

21563231634523 is a deficient number, since it is larger than the sum of its proper divisors (1).

21563231634523 is an equidigital number, since it uses as much as digits as its factorization.

21563231634523 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2332800, while the sum is 46.

The spelling of 21563231634523 in words is "twenty-one trillion, five hundred sixty-three billion, two hundred thirty-one million, six hundred thirty-four thousand, five hundred twenty-three".