660647986 has 4 divisors (see below), whose sum is σ = 990971982. Its totient is φ = 330323992.

The previous prime is 660647909. The next prime is 660647989. The reversal of 660647986 is 689746066.

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

It can be written as a sum of positive squares in only one way, i.e., 659513761 + 1134225 = 25681^2 + 1065^2 .

It is a super-2 number, since 2×660647986² = 872911522811712392, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (660647989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165161995 + ... + 165161998.

Almost surely, 2^660647986 is an apocalyptic number.

660647986 is a deficient number, since it is larger than the sum of its proper divisors (330323996).

660647986 is a wasteful number, since it uses less digits than its factorization.

660647986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330323995.

The product of its (nonzero) digits is 2612736, while the sum is 52.

The square root of 660647986 is about 25703.0734738085. The cubic root of 660647986 is about 870.9436126319.

The spelling of 660647986 in words is "six hundred sixty million, six hundred forty-seven thousand, nine hundred eighty-six".