1644664913 has 2 divisors, whose sum is σ = 1644664914. Its totient is φ = 1644664912.

The previous prime is 1644664891. The next prime is 1644664919. The reversal of 1644664913 is 3194664461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1122451009 + 522213904 = 33503^2 + 22852^2 .

It is a cyclic number.

It is not a de Polignac number, because 1644664913 - 2¹⁶ = 1644599377 is a prime.

It is not a weakly prime, because it can be changed into another prime (1644664919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822332456 + 822332457.

It is an arithmetic number, because the mean of its divisors is an integer number (822332457).

Almost surely, 2^1644664913 is an apocalyptic number.

It is an amenable number.

1644664913 is a deficient number, since it is larger than the sum of its proper divisors (1).

1644664913 is an equidigital number, since it uses as much as digits as its factorization.

1644664913 is an evil number, because the sum of its binary digits is even.

The product of its digits is 373248, while the sum is 44.

The square root of 1644664913 is about 40554.4684714274. The cubic root of 1644664913 is about 1180.3907814676.

The spelling of 1644664913 in words is "one billion, six hundred forty-four million, six hundred sixty-four thousand, nine hundred thirteen".