19776649846721 has 2 divisors, whose sum is σ = 19776649846722. Its totient is φ = 19776649846720.

The previous prime is 19776649846717. The next prime is 19776649846777. The reversal of 19776649846721 is 12764894667791.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19380782374321 + 395867472400 = 4402361^2 + 629180^2 .

It is a cyclic number.

It is not a de Polignac number, because 19776649846721 - 2² = 19776649846717 is a prime.

It is a super-2 number, since 2×19776649846721² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (19776649840721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9888324923360 + 9888324923361.

It is an arithmetic number, because the mean of its divisors is an integer number (9888324923361).

Almost surely, 2^{19776649846721} is an apocalyptic number.

It is an amenable number.

19776649846721 is a deficient number, since it is larger than the sum of its proper divisors (1).

19776649846721 is an equidigital number, since it uses as much as digits as its factorization.

19776649846721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1536288768, while the sum is 77.

The spelling of 19776649846721 in words is "nineteen trillion, seven hundred seventy-six billion, six hundred forty-nine million, eight hundred forty-six thousand, seven hundred twenty-one".