646378467281 has 2 divisors, whose sum is σ = 646378467282. Its totient is φ = 646378467280.

The previous prime is 646378467271. The next prime is 646378467323. The reversal of 646378467281 is 182764873646.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 521585839681 + 124792627600 = 722209^2 + 353260^2 .

It is a cyclic number.

It is not a de Polignac number, because 646378467281 - 2³⁸ = 371500560337 is a prime.

It is a super-2 number, since 2×646378467281² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (646378467221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323189233640 + 323189233641.

It is an arithmetic number, because the mean of its divisors is an integer number (323189233641).

Almost surely, 2^646378467281 is an apocalyptic number.

It is an amenable number.

646378467281 is a deficient number, since it is larger than the sum of its proper divisors (1).

646378467281 is an equidigital number, since it uses as much as digits as its factorization.

646378467281 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 65028096, while the sum is 62.

The spelling of 646378467281 in words is "six hundred forty-six billion, three hundred seventy-eight million, four hundred sixty-seven thousand, two hundred eighty-one".