21635632321 has 2 divisors, whose sum is σ = 21635632322. Its totient is φ = 21635632320.

The previous prime is 21635632307. The next prime is 21635632331. The reversal of 21635632321 is 12323653612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20097031696 + 1538600625 = 141764^2 + 39225^2 .

It is a cyclic number.

It is not a de Polignac number, because 21635632321 - 2⁵ = 21635632289 is a prime.

It is not a weakly prime, because it can be changed into another prime (21635632331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10817816160 + 10817816161.

It is an arithmetic number, because the mean of its divisors is an integer number (10817816161).

Almost surely, 2^21635632321 is an apocalyptic number.

It is an amenable number.

21635632321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21635632321 is an equidigital number, since it uses as much as digits as its factorization.

21635632321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 38880, while the sum is 34.

The spelling of 21635632321 in words is "twenty-one billion, six hundred thirty-five million, six hundred thirty-two thousand, three hundred twenty-one".