643611531356657 has 2 divisors, whose sum is σ = 643611531356658. Its totient is φ = 643611531356656.

The previous prime is 643611531356581. The next prime is 643611531356663. The reversal of 643611531356657 is 756653135116346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 563312297108401 + 80299234248256 = 23734201^2 + 8960984^2 .

It is a cyclic number.

It is not a de Polignac number, because 643611531356657 - 2⁸ = 643611531356401 is a prime.

It is a super-2 number, since 2×643611531356657² (a number of 30 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 643611531356657.

It is not a weakly prime, because it can be changed into another prime (643611531356957) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321805765678328 + 321805765678329.

It is an arithmetic number, because the mean of its divisors is an integer number (321805765678329).

Almost surely, 2^{643611531356657} is an apocalyptic number.

It is an amenable number.

643611531356657 is a deficient number, since it is larger than the sum of its proper divisors (1).

643611531356657 is an equidigital number, since it uses as much as digits as its factorization.

643611531356657 is an evil number, because the sum of its binary digits is even.

The product of its digits is 122472000, while the sum is 62.

The spelling of 643611531356657 in words is "six hundred forty-three trillion, six hundred eleven billion, five hundred thirty-one million, three hundred fifty-six thousand, six hundred fifty-seven".