660820987 has 4 divisors (see below), whose sum is σ = 674881056. Its totient is φ = 646760920.

The previous prime is 660820961. The next prime is 660821011. The reversal of 660820987 is 789028066.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-660820987 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (660820487) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7029964 + ... + 7030057.

It is an arithmetic number, because the mean of its divisors is an integer number (168720264).

Almost surely, 2^660820987 is an apocalyptic number.

660820987 is a deficient number, since it is larger than the sum of its proper divisors (14060069).

660820987 is a wasteful number, since it uses less digits than its factorization.

660820987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14060068.

The product of its (nonzero) digits is 290304, while the sum is 46.

The square root of 660820987 is about 25706.4386292617. The cubic root of 660820987 is about 871.0196293957.

The spelling of 660820987 in words is "six hundred sixty million, eight hundred twenty thousand, nine hundred eighty-seven".