642540857657 has 2 divisors, whose sum is σ = 642540857658. Its totient is φ = 642540857656.

The previous prime is 642540857653. The next prime is 642540857681. The reversal of 642540857657 is 756758045246.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 568932284176 + 73608573481 = 754276^2 + 271309^2 .

It is a cyclic number.

It is not a de Polignac number, because 642540857657 - 2² = 642540857653 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 642540857596 and 642540857605.

It is not a weakly prime, because it can be changed into another prime (642540857653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321270428828 + 321270428829.

It is an arithmetic number, because the mean of its divisors is an integer number (321270428829).

Almost surely, 2^642540857657 is an apocalyptic number.

It is an amenable number.

642540857657 is a deficient number, since it is larger than the sum of its proper divisors (1).

642540857657 is an equidigital number, since it uses as much as digits as its factorization.

642540857657 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 56448000, while the sum is 59.

The spelling of 642540857657 in words is "six hundred forty-two billion, five hundred forty million, eight hundred fifty-seven thousand, six hundred fifty-seven".