646020455681 has 2 divisors, whose sum is σ = 646020455682. Its totient is φ = 646020455680.

The previous prime is 646020455611. The next prime is 646020455683. The reversal of 646020455681 is 186554020646.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 369470681281 + 276549774400 = 607841^2 + 525880^2 .

It is a cyclic number.

It is not a de Polignac number, because 646020455681 - 2²² = 646016261377 is a prime.

It is a super-2 number, since 2×646020455681² (a number of 24 digits) contains 22 as substring.

It is a Sophie Germain prime.

Together with 646020455683, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (646020455683) 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, 323010227840 + 323010227841.

It is an arithmetic number, because the mean of its divisors is an integer number (323010227841).

Almost surely, 2^646020455681 is an apocalyptic number.

It is an amenable number.

646020455681 is a deficient number, since it is larger than the sum of its proper divisors (1).

646020455681 is an equidigital number, since it uses as much as digits as its factorization.

646020455681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1382400, while the sum is 47.

The spelling of 646020455681 in words is "six hundred forty-six billion, twenty million, four hundred fifty-five thousand, six hundred eighty-one".