1644838782121 has 8 divisors (see below), whose sum is σ = 1659463348104. Its totient is φ = 1630215417600.

The previous prime is 1644838782107. The next prime is 1644838782127. The reversal of 1644838782121 is 1212878384461.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 9537475600 + 1635301306521 = 97660^2 + 1278789^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1644838782121 - 2¹¹ = 1644838780073 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1644838782127) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2571355 + ... + 3146671.

It is an arithmetic number, because the mean of its divisors is an integer number (207432918513).

Almost surely, 2^{1644838782121} is an apocalyptic number.

It is an amenable number.

1644838782121 is a deficient number, since it is larger than the sum of its proper divisors (14624565983).

1644838782121 is a wasteful number, since it uses less digits than its factorization.

1644838782121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 600731.

The product of its digits is 4128768, while the sum is 55.

The spelling of 1644838782121 in words is "one trillion, six hundred forty-four billion, eight hundred thirty-eight million, seven hundred eighty-two thousand, one hundred twenty-one".