643958418437 has 2 divisors, whose sum is σ = 643958418438. Its totient is φ = 643958418436.

The previous prime is 643958418431. The next prime is 643958418487. The reversal of 643958418437 is 734814859346.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 348290005921 + 295668412516 = 590161^2 + 543754^2 .

It is a cyclic number.

It is not a de Polignac number, because 643958418437 - 2⁴ = 643958418421 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 643958418437.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643958418431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321979209218 + 321979209219.

It is an arithmetic number, because the mean of its divisors is an integer number (321979209219).

Almost surely, 2^643958418437 is an apocalyptic number.

It is an amenable number.

643958418437 is a deficient number, since it is larger than the sum of its proper divisors (1).

643958418437 is an equidigital number, since it uses as much as digits as its factorization.

643958418437 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 69672960, while the sum is 62.

The spelling of 643958418437 in words is "six hundred forty-three billion, nine hundred fifty-eight million, four hundred eighteen thousand, four hundred thirty-seven".