643499999957 has 2 divisors, whose sum is σ = 643499999958. Its totient is φ = 643499999956.

The previous prime is 643499999953. The next prime is 643500000053. The reversal of 643499999957 is 759999994346.

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., 492739418116 + 150760581841 = 701954^2 + 388279^2 .

It is a cyclic number.

It is not a de Polignac number, because 643499999957 - 2² = 643499999953 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643499999953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321749999978 + 321749999979.

It is an arithmetic number, because the mean of its divisors is an integer number (321749999979).

Almost surely, 2^643499999957 is an apocalyptic number.

It is an amenable number.

643499999957 is a deficient number, since it is larger than the sum of its proper divisors (1).

643499999957 is an equidigital number, since it uses as much as digits as its factorization.

643499999957 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5356925280, while the sum is 83.

The spelling of 643499999957 in words is "six hundred forty-three billion, four hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred fifty-seven".