68587781 has 4 divisors (see below), whose sum is σ = 68606700. Its totient is φ = 68568864.

The previous prime is 68587769. The next prime is 68587811. The reversal of 68587781 is 18778586.

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 20160100 + 48427681 = 4490^2 + 6959^2 .

It is a cyclic number.

It is not a de Polignac number, because 68587781 - 2¹⁰ = 68586757 is a prime.

It is a super-2 number, since 2×68587781² = 9408567405007922, which 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 (68587681) 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, 2126 + ... + 11903.

It is an arithmetic number, because the mean of its divisors is an integer number (17151675).

Almost surely, 2^68587781 is an apocalyptic number.

It is an amenable number.

68587781 is a deficient number, since it is larger than the sum of its proper divisors (18919).

68587781 is a wasteful number, since it uses less digits than its factorization.

68587781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18918.

The product of its digits is 752640, while the sum is 50.

The square root of 68587781 is about 8281.7740249297. The cubic root of 68587781 is about 409.3381767551.

The spelling of 68587781 in words is "sixty-eight million, five hundred eighty-seven thousand, seven hundred eighty-one".