643457 has 2 divisors, whose sum is σ = 643458. Its totient is φ = 643456.

The previous prime is 643453. The next prime is 643463. The reversal of 643457 is 754346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 541696 + 101761 = 736^2 + 319^2 .

It is a cyclic number.

It is not a de Polignac number, because 643457 - 2² = 643453 is a prime.

It is a Chen prime.

It is a d-powerful number, because it can be written as 6⁷ + 4³ + 4⁸ + 3¹¹ + 5⁵ + 7⁶ .

It is not a weakly prime, because it can be changed into another prime (643453) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321728 + 321729.

It is an arithmetic number, because the mean of its divisors is an integer number (321729).

2⁶⁴³⁴⁵⁷ is an apocalyptic number.

It is an amenable number.

643457 is a deficient number, since it is larger than the sum of its proper divisors (1).

643457 is an equidigital number, since it uses as much as digits as its factorization.

643457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10080, while the sum is 29.

The square root of 643457 is about 802.1577151658. The cubic root of 643457 is about 86.3322732420.

Subtracting 643457 from its reverse (754346), we obtain a square (110889 = 333²).

The spelling of 643457 in words is "six hundred forty-three thousand, four hundred fifty-seven".