660655781 has 8 divisors (see below), whose sum is σ = 670408128. Its totient is φ = 650916000.

The previous prime is 660655763. The next prime is 660655813. The reversal of 660655781 is 187556066.

660655781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 660655781 - 2¹⁸ = 660393637 is a prime.

It is a super-2 number, since 2×660655781² = 872932121937439922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660651781) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 177146 + ... + 180836.

It is an arithmetic number, because the mean of its divisors is an integer number (83801016).

Almost surely, 2^660655781 is an apocalyptic number.

It is an amenable number.

660655781 is a deficient number, since it is larger than the sum of its proper divisors (9752347).

660655781 is a wasteful number, since it uses less digits than its factorization.

660655781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6283.

The product of its (nonzero) digits is 302400, while the sum is 44.

The square root of 660655781 is about 25703.2251089236. The cubic root of 660655781 is about 870.9470380460.

The spelling of 660655781 in words is "six hundred sixty million, six hundred fifty-five thousand, seven hundred eighty-one".