643846397 has 2 divisors, whose sum is σ = 643846398. Its totient is φ = 643846396.

The previous prime is 643846393. The next prime is 643846453. The reversal of 643846397 is 793648346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 628053721 + 15792676 = 25061^2 + 3974^2 .

It is a cyclic number.

It is not a de Polignac number, because 643846397 - 2² = 643846393 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643846393) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321923198 + 321923199.

It is an arithmetic number, because the mean of its divisors is an integer number (321923199).

Almost surely, 2^643846397 is an apocalyptic number.

It is an amenable number.

643846397 is a deficient number, since it is larger than the sum of its proper divisors (1).

643846397 is an equidigital number, since it uses as much as digits as its factorization.

643846397 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2612736, while the sum is 50.

The square root of 643846397 is about 25374.1284973494. The cubic root of 643846397 is about 863.4968479096.

The spelling of 643846397 in words is "six hundred forty-three million, eight hundred forty-six thousand, three hundred ninety-seven".