1644225652721 has 2 divisors, whose sum is σ = 1644225652722. Its totient is φ = 1644225652720.

The previous prime is 1644225652691. The next prime is 1644225652723. The reversal of 1644225652721 is 1272565224461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 898256599696 + 745969053025 = 947764^2 + 863695^2 .

It is an emirp because it is prime and its reverse (1272565224461) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1644225652721 - 2²² = 1644221458417 is a prime.

It is a super-3 number, since 3×1644225652721³ (a number of 38 digits) contains 333 as substring.

Together with 1644225652723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1644225652723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822112826360 + 822112826361.

It is an arithmetic number, because the mean of its divisors is an integer number (822112826361).

Almost surely, 2^{1644225652721} is an apocalyptic number.

It is an amenable number.

1644225652721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1644225652721 is an equidigital number, since it uses as much as digits as its factorization.

1644225652721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1612800, while the sum is 47.

The spelling of 1644225652721 in words is "one trillion, six hundred forty-four billion, two hundred twenty-five million, six hundred fifty-two thousand, seven hundred twenty-one".