646259489891 has 2 divisors, whose sum is σ = 646259489892. Its totient is φ = 646259489890.

The previous prime is 646259489881. The next prime is 646259489917. The reversal of 646259489891 is 198984952646.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-646259489891 is a prime.

It is a super-4 number, since 4×646259489891⁴ (a number of 48 digits) contains 4444 as substring.

It is not a weakly prime, because it can be changed into another prime (646259489881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323129744945 + 323129744946.

It is an arithmetic number, because the mean of its divisors is an integer number (323129744946).

Almost surely, 2^646259489891 is an apocalyptic number.

646259489891 is a deficient number, since it is larger than the sum of its proper divisors (1).

646259489891 is an equidigital number, since it uses as much as digits as its factorization.

646259489891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 268738560, while the sum is 71.

The spelling of 646259489891 in words is "six hundred forty-six billion, two hundred fifty-nine million, four hundred eighty-nine thousand, eight hundred ninety-one".