67985507781 has 24 divisors (see below), whose sum is σ = 100328458776. Its totient is φ = 44349603840.

The previous prime is 67985507771. The next prime is 67985507861. The reversal of 67985507781 is 18770558976.

67985507781 is a `hidden beast` number, since 6 + 7 + 9 + 8 + 550 + 7 + 78 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1106892900 + 66878614881 = 33270^2 + 258609^2 .

It is not a de Polignac number, because 67985507781 - 2²⁹ = 67448636869 is a prime.

It is a super-2 number, since 2×67985507781² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (67985507741) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 214860 + ... + 426773.

It is an arithmetic number, because the mean of its divisors is an integer number (4180352449).

Almost surely, 2^67985507781 is an apocalyptic number.

67985507781 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

67985507781 is a deficient number, since it is larger than the sum of its proper divisors (32342950995).

67985507781 is a wasteful number, since it uses less digits than its factorization.

67985507781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 641893 (or 641890 counting only the distinct ones).

The product of its (nonzero) digits is 29635200, while the sum is 63.

The spelling of 67985507781 in words is "sixty-seven billion, nine hundred eighty-five million, five hundred seven thousand, seven hundred eighty-one".