1644518081 has 2 divisors, whose sum is σ = 1644518082. Its totient is φ = 1644518080.

The previous prime is 1644518023. The next prime is 1644518119. The reversal of 1644518081 is 1808154461.

It is an a-pointer prime, because the next prime (1644518119) can be obtained adding 1644518081 to its sum of digits (38).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1598400400 + 46117681 = 39980^2 + 6791^2 .

It is an emirp because it is prime and its reverse (1808154461) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1644518081 - 2⁶ = 1644518017 is a prime.

It is a super-2 number, since 2×1644518081² = 5408879437471845122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1644518011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822259040 + 822259041.

It is an arithmetic number, because the mean of its divisors is an integer number (822259041).

Almost surely, 2^1644518081 is an apocalyptic number.

It is an amenable number.

1644518081 is a deficient number, since it is larger than the sum of its proper divisors (1).

1644518081 is an equidigital number, since it uses as much as digits as its factorization.

1644518081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 30720, while the sum is 38.

The square root of 1644518081 is about 40552.6581249614. The cubic root of 1644518081 is about 1180.3556528737.

The spelling of 1644518081 in words is "one billion, six hundred forty-four million, five hundred eighteen thousand, eighty-one".