1645606651361 has 4 divisors (see below), whose sum is σ = 1645609252500. Its totient is φ = 1645604050224.

The previous prime is 1645606651331. The next prime is 1645606651379. The reversal of 1645606651361 is 1631566065461.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 1639897942225 + 5708709136 = 1280585^2 + 75556^2 .

It is a cyclic number.

It is not a de Polignac number, because 1645606651361 - 2²⁶ = 1645539542497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1645606651321) 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, 329015 + ... + 1843763.

It is an arithmetic number, because the mean of its divisors is an integer number (411402313125).

Almost surely, 2^{1645606651361} is an apocalyptic number.

It is an amenable number.

1645606651361 is a deficient number, since it is larger than the sum of its proper divisors (2601139).

1645606651361 is a wasteful number, since it uses less digits than its factorization.

1645606651361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2601138.

The product of its (nonzero) digits is 2332800, while the sum is 50.

The spelling of 1645606651361 in words is "one trillion, six hundred forty-five billion, six hundred six million, six hundred fifty-one thousand, three hundred sixty-one".