646395977 has 4 divisors (see below), whose sum is σ = 647045316. Its totient is φ = 645746640.

The previous prime is 646395931. The next prime is 646395991. The reversal of 646395977 is 779593646.

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

It can be written as a sum of positive squares in 2 ways, for example, as 320087881 + 326308096 = 17891^2 + 18064^2 .

It is a cyclic number.

It is not a de Polignac number, because 646395977 - 2⁸ = 646395721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646395907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 323174 + ... + 325167.

It is an arithmetic number, because the mean of its divisors is an integer number (161761329).

Almost surely, 2^646395977 is an apocalyptic number.

It is an amenable number.

646395977 is a deficient number, since it is larger than the sum of its proper divisors (649339).

646395977 is an equidigital number, since it uses as much as digits as its factorization.

646395977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 649338.

The product of its digits is 8573040, while the sum is 56.

The square root of 646395977 is about 25424.3186142717. The cubic root of 646395977 is about 864.6351394272.

The spelling of 646395977 in words is "six hundred forty-six million, three hundred ninety-five thousand, nine hundred seventy-seven".