1644909997 has 2 divisors, whose sum is σ = 1644909998. Its totient is φ = 1644909996.

The previous prime is 1644909967. The next prime is 1644910027. The reversal of 1644909997 is 7999094461.

It is a balanced prime because it is at equal distance from previous prime (1644909967) and next prime (1644910027).

It can be written as a sum of positive squares in only one way, i.e., 886788841 + 758121156 = 29779^2 + 27534^2 .

It is a cyclic number.

It is not a de Polignac number, because 1644909997 - 2²³ = 1636521389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1644909967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822454998 + 822454999.

It is an arithmetic number, because the mean of its divisors is an integer number (822454999).

Almost surely, 2^1644909997 is an apocalyptic number.

It is an amenable number.

1644909997 is a deficient number, since it is larger than the sum of its proper divisors (1).

1644909997 is an equidigital number, since it uses as much as digits as its factorization.

1644909997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4408992, while the sum is 58.

The square root of 1644909997 is about 40557.4900234223. The cubic root of 1644909997 is about 1180.4494115515.

The spelling of 1644909997 in words is "one billion, six hundred forty-four million, nine hundred nine thousand, nine hundred ninety-seven".