68213811581 has 4 divisors (see below), whose sum is σ = 68221365564. Its totient is φ = 68206257600.

The previous prime is 68213811563. The next prime is 68213811593. The reversal of 68213811581 is 18511831286.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 56723043556 + 11490768025 = 238166^2 + 107195^2 .

It is a cyclic number.

It is not a de Polignac number, because 68213811581 - 2⁶ = 68213811517 is a prime.

It is a super-2 number, since 2×68213811581² (a number of 22 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 (68213811511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3763430 + ... + 3781511.

It is an arithmetic number, because the mean of its divisors is an integer number (17055341391).

Almost surely, 2^68213811581 is an apocalyptic number.

It is an amenable number.

68213811581 is a deficient number, since it is larger than the sum of its proper divisors (7553983).

68213811581 is an equidigital number, since it uses as much as digits as its factorization.

68213811581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7553982.

The product of its digits is 92160, while the sum is 44.

The spelling of 68213811581 in words is "sixty-eight billion, two hundred thirteen million, eight hundred eleven thousand, five hundred eighty-one".