21681550381363 has 2 divisors, whose sum is σ = 21681550381364. Its totient is φ = 21681550381362.

The previous prime is 21681550381339. The next prime is 21681550381369. The reversal of 21681550381363 is 36318305518612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21681550381363 - 2¹⁷ = 21681550250291 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21681550381363.

It is not a weakly prime, because it can be changed into another prime (21681550381369) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10840775190681 + 10840775190682.

It is an arithmetic number, because the mean of its divisors is an integer number (10840775190682).

Almost surely, 2^{21681550381363} is an apocalyptic number.

21681550381363 is a deficient number, since it is larger than the sum of its proper divisors (1).

21681550381363 is an equidigital number, since it uses as much as digits as its factorization.

21681550381363 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3110400, while the sum is 52.

Adding to 21681550381363 its reverse (36318305518612), we get a palindrome (57999855899975).

The spelling of 21681550381363 in words is "twenty-one trillion, six hundred eighty-one billion, five hundred fifty million, three hundred eighty-one thousand, three hundred sixty-three".