68021666007581 has 16 divisors (see below), whose sum is σ = 81613854298368. Its totient is φ = 55866626443200.

The previous prime is 68021666007563. The next prime is 68021666007623. The reversal of 68021666007581 is 18570066612086.

It is a cyclic number.

It is not a de Polignac number, because 68021666007581 - 2¹⁸ = 68021665745437 is a prime.

It is a super-2 number, since 2×68021666007581² (a number of 28 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (68021666057581) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5060376110 + ... + 5060389551.

It is an arithmetic number, because the mean of its divisors is an integer number (5100865893648).

Almost surely, 2^{68021666007581} is an apocalyptic number.

It is an amenable number.

68021666007581 is a deficient number, since it is larger than the sum of its proper divisors (13592188290787).

68021666007581 is a wasteful number, since it uses less digits than its factorization.

68021666007581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10120765732.

The product of its (nonzero) digits is 5806080, while the sum is 56.

The spelling of 68021666007581 in words is "sixty-eight trillion, twenty-one billion, six hundred sixty-six million, seven thousand, five hundred eighty-one".