6645737641 has 2 divisors, whose sum is σ = 6645737642. Its totient is φ = 6645737640.

The previous prime is 6645737617. The next prime is 6645737671. The reversal of 6645737641 is 1467375466.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5669487616 + 976250025 = 75296^2 + 31245^2 .

It is a cyclic number.

It is not a de Polignac number, because 6645737641 - 2¹³ = 6645729449 is a prime.

It is not a weakly prime, because it can be changed into another prime (6645737671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3322868820 + 3322868821.

It is an arithmetic number, because the mean of its divisors is an integer number (3322868821).

Almost surely, 2^6645737641 is an apocalyptic number.

It is an amenable number.

6645737641 is a deficient number, since it is larger than the sum of its proper divisors (1).

6645737641 is an equidigital number, since it uses as much as digits as its factorization.

6645737641 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2540160, while the sum is 49.

The square root of 6645737641 is about 81521.3937626191. The cubic root of 6645737641 is about 1880.1004964574.

The spelling of 6645737641 in words is "six billion, six hundred forty-five million, seven hundred thirty-seven thousand, six hundred forty-one".