1644138401551 has 16 divisors (see below), whose sum is σ = 1659733244928. Its totient is φ = 1628592565600.

The previous prime is 1644138401459. The next prime is 1644138401617. The reversal of 1644138401551 is 1551048314461.

It is a cyclic number.

It is not a de Polignac number, because 1644138401551 - 2²¹ = 1644136304399 is a prime.

It is a super-3 number, since 3×1644138401551³ (a number of 38 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1644138401498 and 1644138401507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1644138401351) 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 in 15 ways as a sum of consecutive naturals, for example, 191776701 + ... + 191785273.

It is an arithmetic number, because the mean of its divisors is an integer number (103733327808).

Almost surely, 2^{1644138401551} is an apocalyptic number.

1644138401551 is a deficient number, since it is larger than the sum of its proper divisors (15594843377).

1644138401551 is a wasteful number, since it uses less digits than its factorization.

1644138401551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11222.

The product of its (nonzero) digits is 230400, while the sum is 43.

The spelling of 1644138401551 in words is "one trillion, six hundred forty-four billion, one hundred thirty-eight million, four hundred one thousand, five hundred fifty-one".