668140081537 has 2 divisors, whose sum is σ = 668140081538. Its totient is φ = 668140081536.

The previous prime is 668140081519. The next prime is 668140081559. The reversal of 668140081537 is 735180041866.

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., 423594007281 + 244546074256 = 650841^2 + 494516^2 .

It is a cyclic number.

It is not a de Polignac number, because 668140081537 - 2²³ = 668131692929 is a prime.

It is a super-2 number, since 2×668140081537² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (668140081577) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334070040768 + 334070040769.

It is an arithmetic number, because the mean of its divisors is an integer number (334070040769).

Almost surely, 2^668140081537 is an apocalyptic number.

It is an amenable number.

668140081537 is a deficient number, since it is larger than the sum of its proper divisors (1).

668140081537 is an equidigital number, since it uses as much as digits as its factorization.

668140081537 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 967680, while the sum is 49.

The spelling of 668140081537 in words is "six hundred sixty-eight billion, one hundred forty million, eighty-one thousand, five hundred thirty-seven".