646517985 has 16 divisors (see below), whose sum is σ = 1036043136. Its totient is φ = 344271488.

The previous prime is 646517981. The next prime is 646517999. The reversal of 646517985 is 589715646.

It is a cyclic number.

It is not a de Polignac number, because 646517985 - 2² = 646517981 is a prime.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (646517981) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23604 + ... + 43013.

It is an arithmetic number, because the mean of its divisors is an integer number (64752696).

Almost surely, 2^646517985 is an apocalyptic number.

It is an amenable number.

646517985 is a deficient number, since it is larger than the sum of its proper divisors (389525151).

646517985 is a wasteful number, since it uses less digits than its factorization.

646517985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67272.

The product of its digits is 1814400, while the sum is 51.

The square root of 646517985 is about 25426.7179360609. The cubic root of 646517985 is about 864.6895363043.

The spelling of 646517985 in words is "six hundred forty-six million, five hundred seventeen thousand, nine hundred eighty-five".