646342243681 has 2 divisors, whose sum is σ = 646342243682. Its totient is φ = 646342243680.

The previous prime is 646342243633. The next prime is 646342243727. The reversal of 646342243681 is 186342243646.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 615157862400 + 31184381281 = 784320^2 + 176591^2 .

It is a cyclic number.

It is not a de Polignac number, because 646342243681 - 2¹³ = 646342235489 is a prime.

It is a super-2 number, since 2×646342243681² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (646342241681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323171121840 + 323171121841.

It is an arithmetic number, because the mean of its divisors is an integer number (323171121841).

Almost surely, 2^646342243681 is an apocalyptic number.

It is an amenable number.

646342243681 is a deficient number, since it is larger than the sum of its proper divisors (1).

646342243681 is an equidigital number, since it uses as much as digits as its factorization.

646342243681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3981312, while the sum is 49.

The spelling of 646342243681 in words is "six hundred forty-six billion, three hundred forty-two million, two hundred forty-three thousand, six hundred eighty-one".