66706836781 has 32 divisors (see below), whose sum is σ = 73470136320. Its totient is φ = 60195096000.

The previous prime is 66706836769. The next prime is 66706836817. The reversal of 66706836781 is 18763860766.

It is not a de Polignac number, because 66706836781 - 2⁹ = 66706836269 is a prime.

It is a super-3 number, since 3×66706836781³ (a number of 33 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66706836751) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 68698626 + ... + 68699596.

It is an arithmetic number, because the mean of its divisors is an integer number (2295941760).

Almost surely, 2^66706836781 is an apocalyptic number.

It is an amenable number.

66706836781 is a deficient number, since it is larger than the sum of its proper divisors (6763299539).

66706836781 is a wasteful number, since it uses less digits than its factorization.

66706836781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1657.

The product of its (nonzero) digits is 12192768, while the sum is 58.

The spelling of 66706836781 in words is "sixty-six billion, seven hundred six million, eight hundred thirty-six thousand, seven hundred eighty-one".