1644453913 has 2 divisors, whose sum is σ = 1644453914. Its totient is φ = 1644453912.

The previous prime is 1644453827. The next prime is 1644453947. The reversal of 1644453913 is 3193544461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 822370329 + 822083584 = 28677^2 + 28672^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1644453913 is a prime.

It is not a weakly prime, because it can be changed into another prime (1644453113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822226956 + 822226957.

It is an arithmetic number, because the mean of its divisors is an integer number (822226957).

Almost surely, 2^1644453913 is an apocalyptic number.

It is an amenable number.

1644453913 is a deficient number, since it is larger than the sum of its proper divisors (1).

1644453913 is an equidigital number, since it uses as much as digits as its factorization.

1644453913 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 155520, while the sum is 40.

The square root of 1644453913 is about 40551.8669483909. The cubic root of 1644453913 is about 1180.3403004436.

The spelling of 1644453913 in words is "one billion, six hundred forty-four million, four hundred fifty-three thousand, nine hundred thirteen".