1644001397 has 2 divisors, whose sum is σ = 1644001398. Its totient is φ = 1644001396.

The previous prime is 1644001361. The next prime is 1644001421. The reversal of 1644001397 is 7931004461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 845995396 + 798006001 = 29086^2 + 28249^2 .

It is a cyclic number.

It is not a de Polignac number, because 1644001397 - 2²⁶ = 1576892533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1644051397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822000698 + 822000699.

It is an arithmetic number, because the mean of its divisors is an integer number (822000699).

Almost surely, 2^1644001397 is an apocalyptic number.

It is an amenable number.

1644001397 is a deficient number, since it is larger than the sum of its proper divisors (1).

1644001397 is an equidigital number, since it uses as much as digits as its factorization.

1644001397 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18144, while the sum is 35.

The square root of 1644001397 is about 40546.2870926550. The cubic root of 1644001397 is about 1180.2320229850.

The spelling of 1644001397 in words is "one billion, six hundred forty-four million, one thousand, three hundred ninety-seven".