1989812064221 has 2 divisors, whose sum is σ = 1989812064222. Its totient is φ = 1989812064220.

The previous prime is 1989812064217. The next prime is 1989812064311. The reversal of 1989812064221 is 1224602189891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1051877923321 + 937934140900 = 1025611^2 + 968470^2 .

It is an emirp because it is prime and its reverse (1224602189891) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1989812064221 - 2² = 1989812064217 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1989812054221) 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, 994906032110 + 994906032111.

It is an arithmetic number, because the mean of its divisors is an integer number (994906032111).

Almost surely, 2^{1989812064221} is an apocalyptic number.

It is an amenable number.

1989812064221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1989812064221 is an equidigital number, since it uses as much as digits as its factorization.

1989812064221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 995328, while the sum is 53.

The spelling of 1989812064221 in words is "one trillion, nine hundred eighty-nine billion, eight hundred twelve million, sixty-four thousand, two hundred twenty-one".