21216401206337 has 2 divisors, whose sum is σ = 21216401206338. Its totient is φ = 21216401206336.

The previous prime is 21216401206291. The next prime is 21216401206393. The reversal of 21216401206337 is 73360210461212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18671352113296 + 2545049093041 = 4321036^2 + 1595321^2 .

It is a cyclic number.

It is not a de Polignac number, because 21216401206337 - 2²⁸ = 21216132770881 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21216401206337.

It is not a weakly prime, because it can be changed into another prime (21216401206237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10608200603168 + 10608200603169.

It is an arithmetic number, because the mean of its divisors is an integer number (10608200603169).

Almost surely, 2^{21216401206337} is an apocalyptic number.

It is an amenable number.

21216401206337 is a deficient number, since it is larger than the sum of its proper divisors (1).

21216401206337 is an equidigital number, since it uses as much as digits as its factorization.

21216401206337 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72576, while the sum is 38.

Adding to 21216401206337 its reverse (73360210461212), we get a palindrome (94576611667549).

The spelling of 21216401206337 in words is "twenty-one trillion, two hundred sixteen billion, four hundred one million, two hundred six thousand, three hundred thirty-seven".