21218365657337 has 2 divisors, whose sum is σ = 21218365657338. Its totient is φ = 21218365657336.

The previous prime is 21218365657327. The next prime is 21218365657421. The reversal of 21218365657337 is 73375656381212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21133686985321 + 84678672016 = 4597139^2 + 290996^2 .

It is a cyclic number.

It is not a de Polignac number, because 21218365657337 - 2⁸ = 21218365657081 is a prime.

It is not a weakly prime, because it can be changed into another prime (21218365657327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10609182828668 + 10609182828669.

It is an arithmetic number, because the mean of its divisors is an integer number (10609182828669).

Almost surely, 2^{21218365657337} is an apocalyptic number.

It is an amenable number.

21218365657337 is a deficient number, since it is larger than the sum of its proper divisors (1).

21218365657337 is an equidigital number, since it uses as much as digits as its factorization.

21218365657337 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38102400, while the sum is 59.

The spelling of 21218365657337 in words is "twenty-one trillion, two hundred eighteen billion, three hundred sixty-five million, six hundred fifty-seven thousand, three hundred thirty-seven".