21605311327 has 2 divisors, whose sum is σ = 21605311328. Its totient is φ = 21605311326.

The previous prime is 21605311297. The next prime is 21605311361. The reversal of 21605311327 is 72311350612.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21605311327 - 2²³ = 21596922719 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21605311397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10802655663 + 10802655664.

It is an arithmetic number, because the mean of its divisors is an integer number (10802655664).

Almost surely, 2^21605311327 is an apocalyptic number.

21605311327 is a deficient number, since it is larger than the sum of its proper divisors (1).

21605311327 is an equidigital number, since it uses as much as digits as its factorization.

21605311327 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7560, while the sum is 31.

Adding to 21605311327 its reverse (72311350612), we get a palindrome (93916661939).

The spelling of 21605311327 in words is "twenty-one billion, six hundred five million, three hundred eleven thousand, three hundred twenty-seven".