21644668337 has 2 divisors, whose sum is σ = 21644668338. Its totient is φ = 21644668336.

The previous prime is 21644668327. The next prime is 21644668363. The reversal of 21644668337 is 73386644612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17913413281 + 3731255056 = 133841^2 + 61084^2 .

It is a cyclic number.

It is not a de Polignac number, because 21644668337 - 2⁸ = 21644668081 is a prime.

It is not a weakly prime, because it can be changed into another prime (21644668327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10822334168 + 10822334169.

It is an arithmetic number, because the mean of its divisors is an integer number (10822334169).

Almost surely, 2^21644668337 is an apocalyptic number.

It is an amenable number.

21644668337 is a deficient number, since it is larger than the sum of its proper divisors (1).

21644668337 is an equidigital number, since it uses as much as digits as its factorization.

21644668337 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3483648, while the sum is 50.

The spelling of 21644668337 in words is "twenty-one billion, six hundred forty-four million, six hundred sixty-eight thousand, three hundred thirty-seven".