1621644639389 has 4 divisors (see below), whose sum is σ = 1665472872924. Its totient is φ = 1577816405856.

The previous prime is 1621644639379. The next prime is 1621644639413. The reversal of 1621644639389 is 9839364461261.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1364527696900 + 257116942489 = 1168130^2 + 507067^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621644639389 - 2⁸ = 1621644639133 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621644639379) 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 3 ways as a sum of consecutive naturals, for example, 21914116712 + ... + 21914116785.

It is an arithmetic number, because the mean of its divisors is an integer number (416368218231).

Almost surely, 2^{1621644639389} is an apocalyptic number.

It is an amenable number.

1621644639389 is a deficient number, since it is larger than the sum of its proper divisors (43828233535).

1621644639389 is an equidigital number, since it uses as much as digits as its factorization.

1621644639389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43828233534.

The product of its digits is 40310784, while the sum is 62.

The spelling of 1621644639389 in words is "one trillion, six hundred twenty-one billion, six hundred forty-four million, six hundred thirty-nine thousand, three hundred eighty-nine".