1644865797 has 16 divisors (see below), whose sum is σ = 2265546752. Its totient is φ = 1060432560.

The previous prime is 1644865751. The next prime is 1644865811. The reversal of 1644865797 is 7975684461.

It is not a de Polignac number, because 1644865797 - 2⁷ = 1644865669 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 (1644865727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 140088 + ... + 151374.

It is an arithmetic number, because the mean of its divisors is an integer number (141596672).

Almost surely, 2^1644865797 is an apocalyptic number.

It is an amenable number.

1644865797 is a deficient number, since it is larger than the sum of its proper divisors (620680955).

1644865797 is a wasteful number, since it uses less digits than its factorization.

1644865797 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12888.

The product of its digits is 10160640, while the sum is 57.

The square root of 1644865797 is about 40556.9451142465. The cubic root of 1644865797 is about 1180.4388382615.

The spelling of 1644865797 in words is "one billion, six hundred forty-four million, eight hundred sixty-five thousand, seven hundred ninety-seven".