18896539721 has 2 divisors, whose sum is σ = 18896539722. Its totient is φ = 18896539720.

The previous prime is 18896539589. The next prime is 18896539729. The reversal of 18896539721 is 12793569881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16935378496 + 1961161225 = 130136^2 + 44285^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18896539721 is a prime.

It is not a weakly prime, because it can be changed into another prime (18896539729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9448269860 + 9448269861.

It is an arithmetic number, because the mean of its divisors is an integer number (9448269861).

Almost surely, 2^18896539721 is an apocalyptic number.

It is an amenable number.

18896539721 is a deficient number, since it is larger than the sum of its proper divisors (1).

18896539721 is an equidigital number, since it uses as much as digits as its factorization.

18896539721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6531840, while the sum is 59.

The spelling of 18896539721 in words is "eighteen billion, eight hundred ninety-six million, five hundred thirty-nine thousand, seven hundred twenty-one".